µ-LED, µ-LED DEVICE, DISPLAY AND METHOD FOR THE SAME

ABSTRACT

The invention relates to various aspects of a μ-LED or a μ-LED array for augmented reality or lighting applications, in particular in the automotive field. The μ-LED is characterized by particularly small dimensions in the range of a few μm.

This patent application is a continuation of and claims the benefit ofU.S. application Ser. No. 17/039,422 filed 30 Sep. 2020, which claimsthe priorities of the German applications, DE 10 2019 118 082.1 of 4Jul. 2019, DE 10 2019 130 934.4 of 15 Nov. 2019, DE 10 2019 116 312.9 of14 Jun. 2019, DE 10 2019 118 085.6 of 4 Jul. 2019, DE 10 2019 113 793.4of 23 May 2019, as well as the priority of the Danish applications DKPA201970059 of 29 Jan. 2019 and PCT application PCT/EP2020/052191 of 29Jan. 2020. The disclosure of each of the above-noted applications isincorporated herein by reference in its entirety. Additionally, thispatent application is related to the following co-pending patentapplications: U.S. application Ser. No. 17/038,283, entitled “μ-LED,μ-LED Device, Display and Method for the Same,” filed Sep. 30, 2020;U.S. application Ser. No. 17/039,283, entitled “μ-LED, μ-LED Device,Display and Method for the Same,” filed Sep. 30, 2020; U.S. applicationSer. No. 17/039,097, entitled “μ-LED, μ-LED Device, Display and Methodfor the Same,” filed Sep. 30, 2020; U.S. application Ser. No.17/039,482, entitled “μ-LED, μ-LED Device, Display and Method for theSame,” filed Sep. 30, 2020; U.S. application Ser. No. 17/426,456,entitled “μ-LED, μ-LED Device, Display and Method for the Same,” filedJul. 28, 2021; U.S. application Ser. No. 17/426,520, entitled “μ-LED,μ-LED Device, Display and Method for the Same,” filed Jul. 28, 2021; andU.S. application Ser. No. ______ (Docket No. 041299.00017), entitled“μ-LED, μ-LED Device, Display and Method for the Same,” filed Sep. 14,2021.

BACKGROUND

The ongoing current developments within the Internet of Things and thefield of communication have opened the door for various new applicationsand concepts. For development, service and manufacturing purposes, theseconcepts and applications offer increased effectiveness and efficiency.

One aspect of new concepts is based on augmented or virtual reality. Ageneral definition of “augmented reality” is given by an “interactiveexperience of the real environment, whereby the objects from it, whichare in the real world, are augmented by computer generated perceptibleinformation”.

The information is mostly transported by visualization, but is notlimited to visual perception. Sometimes haptic or other sensoryperceptions can be used to expand reality. In the case of visualization,the superimposed sensory-visual information can be constructive, i.e.additional to the natural environment, or it can be destructive, forexample by obscuring parts of the natural environment. In someapplications, it is also possible to interact with the superimposedsensory information in one way or another. In this way, augmentedreality reinforces the ongoing perception of the user of the realenvironment.

In contrast, “virtual reality” completely replaces the real environmentof the user with an environment that is completely simulated. In otherwords, while in an augmented reality environment the user is able toperceive the real world at least partially, in a virtual reality theenvironment is completely simulated and may differ significantly fromreality.

Augmented Reality can be used to improve natural environmentalsituations, enriching the user's experience or supporting the user inperforming certain tasks. For example, a user may use a display withaugmented reality features to assist him in performing certain tasks.Because information about a real object is superimposed to provide cluesto the user, the user is supported with additional information, allowingthe user to act more quickly, safely and effectively duringmanufacturing, repair or other services. In the medical field, augmentedreality can be used to guide and support the doctor in diagnosing andtreating the patient. In development, an engineer may experience theresults of his experiments directly and can therefore evaluate theresults more easily. In the tourism or event industry, augmented realitycan provide a user with additional information about sights, history,and the like. Augmented Reality can support the learning of activitiesor tasks.

SUMMARY

In the following summary different aspects for μ-displays in theautomotive and augmented reality applications are explained. Thisincludes devices, displays, controls, process engineering methods andother aspects suitable for augmented reality and automotiveapplications. This includes aspects which are directed to lightgeneration by means of displays, indicators or similar. In addition,control circuits, power supplies and aspects of light extraction, lightguidance and focusing as well as applications of such devices are listedand explained by means of various examples.

Because of the various limitations and challenges posed by the smallsize of the light-generating components, a combination of the variousaspects is not only advantageous, but often necessary. For ease ofreference, this disclosure is divided into several sections with similartopics. However, this should explicitly not be understood to mean thatfeatures from one topic cannot be combined with others. Rather, aspectsfrom different topics should be combined to create a display foraugmented reality or other applications or even in the automotivesector.

For considerations of the following solutions, some terms andexpressions should be explained in order to define a common and equalunderstanding. The terms listed are generally used with thisunderstanding in this document. In individual cases, however, there maybe deviations from the interpretation, whereby such deviation will bespecifically referred to.

“Active Matrix Display”

The term “active matrix display” was originally used for liquid crystaldisplays containing a matrix of thin film transistors that drive LCDpixels. Each individual pixel has a circuit with active components(usually transistors) and power supply connections. At present, however,this technology should not be limited to liquid crystals, but shouldalso be used in particular for driving μ-LEDs or μ-displays.

“Active Matrix Carrier Substrate”

“Active matrix carrier substrate” or “active matrix backplane” means adrive for light emitting diodes of a display with thin-film transistorcircuits. The circuits may be integrated into the backplane or mountedon it. The “active matrix carrier substrate” has one or more interfacecontacts, which form an electrical connection to a μ-LED displaystructure. An “active-matrix carrier substrate” can thus be part of anactive-matrix display or support it.

“Active Layer”

The active layer is referred to as the layer in an optoelectroniccomponent or light emitting diode in which charge carriers recombine. Inits simplest form, the active layer can be characterized by a region oftwo adjacent semiconductor layers of different conductivity type. Morecomplex active layers comprise quantum wells (see there), multi-quantumwells or other structures that have additional properties. Similarly,the structure and material systems can be used to adjust the band gap(see there) in the active layer, which determines the wavelength andthus the color of the light.

“Alvarez Lens Array”

With the use of Alvarez lens pairs, a beam path can be adapted to videoeyewear. An adjustment optic comprises an Alvarez lens arrangement, inparticular a rotatable version with a Moire lens arrangement. Here, thebeam deflection is determined by the first derivative of the respectivephase plate relief, which is approximated, for example, byz=ax2+by2+cx+dy+e for the transmission direction z and the transversedirections x and y, and by the offset of the two phase plates arrangedin pairs in the transverse directions x and y. For further designalternatives, swiveling prisms are provided in the adjustment optics.

“Augmented Reality (AR)”

This is an interactive experience of the real environment, where thesubject of the picking up is located in the real world and is enhancedby computer-generated perceptible information. Extended reality is thecomputer-aided extension of the perception of reality by means of thiscomputer-generated perceptible information. The information can addressall human sensory modalities. Often, however, augmented reality is onlyunderstood to be the visual representation of information, i.e. thesupplementation of images or videos with computer-generated additionalinformation or virtual objects by means of fade-in/overlay.

Applications and explanations of the mode of operation of AugmentedReality can be found in the introduction and in the following inexecution examples.

“Automotive.”

Automotive generally refers to the motor vehicle or automobile industry.This term should therefore cover this branch, but also all otherbranches of industry which include μ-displays or generally lightdisplays—with very high resolution and μ-LEDs.

“Bandgap”

Bandgap, also known as band gap or forbidden zone, is the energeticdistance between the valence band and conduction band of a solid-statebody. Its electrical and optical properties are largely determined bythe size of the band gap. The size of the band gap is usually specifiedin electron volts (eV). The band gap is thus also used to differentiatebetween metals, semiconductors and insulators. The band gap can beadapted, i.e. changed, by various measures such as spatial doping,deforming of the crystal lattice structure or by changing the materialsystems. Material systems with so-called direct band gap, i.e. where themaximum of the valence band and a minimum of the conduction band in thepulse space are superimposed, allow a recombination of electron-holepairs under emission of light.

“Bragg Grid”

Fibre Bragg gratings are special optical interference filters inscribedin optical fibres. Wavelengths that lie within the filter bandwidtharound AB are reflected. In the fiber core of an optical waveguide, aperiodic modulation of the refractive index is generated by means ofvarious methods. This creates areas with high and low refractive indexesthat reflect light of a certain wavelength (bandstop). The centerwavelength of the filter bandwidth in single-mode fibers results fromthe Bragg condition.

“Directionality”

Directionality is the term used to describe the radiation pattern of aμ-LED or other light-emitting device. A high directionality correspondsto a high directional radiation, or a small radiation cone. In general,the aim should be to obtain a high directional radiation so thatcrosstalk of light into adjacent pixels is avoided as far as possible.Accordingly, the light-emitting component has a different brightnessdepending on the viewing angle and thus differs from a Lambert emitter.The directionality can be changed by mechanical measures or othermeasures, for example on the side intended for the emission. In additionto lenses and the like, this includes photonic crystals or pillarstructures (columnar structures) arranged on the emitting surface of apixelated array or on an arrangement of, in particular, μ-LEDs. Thesegenerate a virtual band gap that reduces or prevents the propagation ofa light vector along the emitting surface.

“Far Field”

The terms near field and far field describe spatial areas around acomponent emitting an electromagnetic wave, which differ in theircharacterization. Usually the space regions are divided into threeareas: reactive near field, transition field and far field. In the farfield, the electromagnetic wave propagates as a plane wave independentof the radiating element.

“Fly Screen Effect”

The Screen Door Effect (SDE) is a permanently visible image artefact indigital video projectors. The term fly screen effect describes theunwanted black space between the individual pixels or their projectedinformation, which is caused by technical reasons, and takes the form ofa fly screen. This distance is due to the construction, because betweenthe individual LCD segments run the conductor paths for control, wherelight is swallowed and therefore cannot hit the screen. If smalloptoelectronic lighting devices and especially μ-LEDs are used or if thedistance between individual light emitting diodes is too great, theresulting low packing density leads to possibly visible differencesbetween pointy illuminated and dark areas when viewing a single pixelarea. This so-called fly screen effect (screen door effect) isparticularly noticeable at a short viewing distance and thus especiallyin applications such as VR glasses. Sub-pixel structures are usuallyperceived and perceived as disturbing when the illumination differencewithin a pixel continues periodically across the matrix arrangement.Accordingly, the fly screen effect in automotive and augmented realityapplications should be avoided as far as possible.

“Flip Chip”

Flip-chip assembly is a process of assembly and connection technologyfor contacting unpackaged semiconductor chips by means of contact bumps,or short “bumps”. In flip-chip mounting, the chip is mounted directly,without any further connecting wires, with the active contacting sidedown—towards the substrate/circuit carrier—via the bumps. This resultsin particularly small package dimensions and short conductor lengths. Aflip-chip is thus in particular an electronic semiconductor componentcontacted on its rear side. The mounting may also require specialtransfer techniques, for example using an auxiliary carrier. Theradiation direction of a flip chip is then usually the side opposite thecontact surfaces.

“Flip-Flop”

A flip-flop, often called a bi-stable flip-flop or bi-stable flip-flopelement, is an electronic circuit that has two stable states of theoutput signal. The current state depends not only on the input signalspresent at the moment, but also on the state that existed prior to thetime under consideration. A dependence on time does not exist, but onlyon events. Due to the bi-stability, the flip-flop can store a dataquantity of a single bit for an unlimited time. In contrast to othertypes of storage, however, power supply must be permanently guaranteed.The flip-flop, as the basic component of sequential circuits, is anindispensable component of digital technology and thus a fundamentalcomponent of many electronic circuits, from quartz watches tomicroprocessors. In particular, as an elementary one-bit memory, it isthe basic element of static memory components for computers. Somedesigns can use different types of flip-flops or other buffer circuitsto store state information. Their respective input and output signalsare digital, i.e. they alternate between logical “false” and logical“true”. These values are also known as “low” 0 and “high” 1.

“Head-Up Display”

The head-up display is a display system or projection device that allowsusers to maintain their head position or viewing direction by projectinginformation into their field of vision. The Head-up Display is anaugmented reality system. In some cases, a Head-Up Display has a sensorto determine the direction of vision or orientation in space.

“Horizontal Light Emitting Diode”

With horizontal LEDs, the electrical connections are on a common side ofthe LED. This is often the back of the LED facing away from the lightemission surface. Horizontal LEDs therefore have contacts that are onlyformed on one surface side.

“Interference Filter”

Interference filters are optical components that use the effect ofinterference to filter light according to frequency, i.e. color forvisible light.

“Collimation”

In optics, collimation refers to the parallel direction of divergentlight beams. The corresponding lens is called collimator or convergentlens. A collimated light beam contains a large proportion of parallelrays and is therefore minimally spread when it spreads. A use in thissense refers to the spreading of light emitted by a source. A collimatedbeam emitted from a surface has a strong dependence on the angle ofradiation. In other words, the radiance (power per unit of a fixed angleper unit of projected source area) of a collimated light source changeswith increasing angle. Light can be collimated by a number of methods,for example by using a special lens placed in front of the light source.Consequently, collimated light can also be considered as light with avery high directional dependence.

“Converter Material”

Converter material is a material, which is suitable for converting lightof a first wavelength into a second wavelength. The first wavelength isshorter than the second wavelength. This includes various stableinorganic as well as organic dyes and quantum dots. The convertermaterial can be applied and structured in various processes.

“Lambert Lamps”

For many applications, a so-called Lambertian radiation pattern isrequired. This means that a light-emitting surface ideally has a uniformradiation density over its area, resulting in a vertically circulardistribution of radiant intensity. Since the human eye only evaluatesthe luminance (luminance is the photometric equivalent of radiance),such a Lambertian material appears to be equally bright regardless ofthe direction of observation. Especially for curved and flexible displaysurfaces, this uniform, angle-independent brightness can be an importantquality factor that is sometimes difficult to achieve with currentlyavailable displays due to their design and LED technology.

LEDs and μ-LEDs resemble a Lambert spotlight and emit light in a largespatial angle. Depending on the application, further measures are takento improve the radiation characteristics or to achieve greaterdirectionality (see there).

“Conductivity Type”

The term “conductivity type” refers to the majority of (n- or p-) chargecarriers in a given semiconductor material. In other words, asemiconductor material that is n-doped is considered to be of n-typeconductivity. Accordingly, if a semiconductor material is n-type, thenit is n-doped. The term “active” region in a semiconductor refers to aborder region in a semiconductor between an n-doped layer and a p-dopedlayer. In this region, a radiative recombination of p- and n-type chargecarriers takes place. In some designs, the active region is stillstructured and includes, for example, quantum well or quantum dotstructures.

“Light Field Display”

Virtual retinal display (VNA) or light field display is referred to adisplay technology that draws a raster image directly onto the retina ofthe eye. The user gets the impression of a screen floating in front ofhim. A light field display can be provided in the form of glasses,whereby a raster image is projected directly onto the retina of a user'seye. In the virtual retina display, a direct retinal projection createsan image within the user's eye. The light field display is an augmentedreality system.

“Lithography” or “Photolithography”

Photolithography is one of the central methods of semiconductor andmicrosystem technology for the production of integrated circuits andother products. The image of a photomask is transferred onto aphotosensitive photoresist by means of exposure. Afterwards, the exposedareas of the photoresist are dissolved (alternatively, the unexposedareas can be dissolved if the photoresist is cured under light). Thiscreates a lithographic mask that allows further processing by chemicaland physical processes, such as applying material to the open areas oretching depressions in the open areas. Later, the remaining photoresistcan also be removed.

“μ-LED”

A μ-LED is an optoelectronic component whose edge lengths are less than70 μm, especially down to less than 20 μm, especially in the range of 1μm to 10 μm. Another range is between 10 to 30 μm. This results in anarea of a few hundred μm² down to several tens of μm². For example, aμ-LED can comprise an area of about 60 μm² with an edge length of about8 μm. In some cases, a μ-LED has an edge length of 5 μm or less,resulting in a size of less than 30 μm². Typical heights of such μ-LEDsare, for example, in the range of 1.5 μm to 10 μm.

In addition to classic lighting applications, displays are the mainapplications for μ-LEDs. The μ-LEDs form pixels or subpixels and emitlight of a defined color. Due to their small pixel size and high densitywith a small pitch, μ-LEDs are suitable for small monolithic displaysfor AR applications, among other things.

Due to the above-mentioned very small size of a μ-LED, the productionand processing is significantly more difficult compared to previouslarger LEDs. The same applies to additional elements such as contacts,package, lenses etc. Some aspects that can be realized with largeroptoelectronic components cannot be produced with μ-LEDs or only in adifferent way. In this respect, a μ-LED is therefore significantlydifferent from a conventional LED, i.e. a light emitting device with anedge length of 200 μm or more.

“μ-LED Array”

See at μ-Display

“μ-Display”

A μ-display or μ-LED array is a matrix with a plurality of pixelsarranged in defined rows and columns. With regard to its functionality,a μ-LED array often forms a matrix of μ-LEDs of the same type and color.Therefore, it rather provides a lighting surface. The purpose of aμ-display, on the other hand, is to transmit information, which oftenresults in the demand for different colors or an addressable control foreach individual pixel or subpixel. A μ-display can be made up of severalμ-LED arrays, which are arranged together on a backplane or othercarrier. Likewise, a μ-LED array can also form a μ-Display.

The size of each pixel is in the order of a few μm, similar to μ-LEDs.Consequently, the overall dimension of a p display with 1920*1080 pixelswith a μ-LED size of 5 μm per pixel and directly adjacent pixels is inthe order of a few 10 mm². In other words, a μ-display or μ-LED array isa small-sized arrangement, which is realized by means of μ-LEDs.

μ-displays or μ-LED arrays can be formed from the same, i.e. from onework piece. The μ-LEDs of the μ-LED array can be monolithic. Suchμ-displays or μ-LED arrays are called monolithic μ-LED arrays orμ-displays.

Alternatively, both assemblies can be formed by growing μ-LEDsindividually on a substrate and then arranging them individually or ingroups on a carrier at a desired distance from each other using aso-called Pick & Place process. Such μ-displays or μ-LED arrays arecalled non-monolithic. For non-monolithic μ-displays or μ-LED arrays,other distances between individual μ-LEDs are also possible. Thesedistances can be chosen flexibly depending on the application anddesign. Thus, such μ-displays or μ-LED arrays can also be calledpitch-expanded. In the case of pitch-expanded μ-displays or μ-LEDarrays, this means that the μ-LEDs are arranged at a greater distancethan on the growth substrate when transferred to a carrier. In anon-monolithic μ-display or μ-LED array, each individual pixel cancomprise a blue light-emitting μ-LED and a green light-emitting μ-LED aswell as a red light-emitting μ-LED.

To take advantage of different advantages of monolithic μ-LED arrays andnon-monolithic μ-LED arrays in a single module, monolithic μ-LED arrayscan be combined with non-monolithic μ-LED arrays in a μ-display. Thus,μ-displays can be used to realize different functions or applications.Such a display is called a hybrid display.

“μ-LED Nano Column”

A μ-LED nano column is generally a stack of semiconductor layers with anactive layer, thus forming a μ-LED. The μ-LED nano column has an edgelength smaller than the height of the column. For example, the edgelength of a μ-LED nanopillar is approximately 10 nm to 300 nm, while theheight of the device can be in the range of 200 nm to 1 μm or more.

“μ-Rod”

μ-rod or Rod designates in particular a geometric structure, inparticular a rod or bar or generally a longitudinally extending, forexample cylindrical, structure. μ-rods are produced with spatialdimensions in the μm to nanometer range. Thus, nanorods are alsoincluded here.

“Nanorods”

In nanotechnology, nanorods are a design of nanoscale objects. Each oftheir dimensions is in the range of about 10 nm to 500 nm. They may besynthesized from metal or semiconducting materials. Aspect ratios(length divided by width) are 3 to 5. Nanorods are produced by directchemical synthesis. A combination of ligands acts as a shape controlagent and attaches to different facets of the nanorod with differentstrengths. This allows different shapes of the nanorod with differentgrowth rates to produce an elongated object. μLED nanopillars are suchnanorods.

“Miniature LED”

Their dimensions range from 100 μm to 750 μm, especially in the rangelarger than 150 μm.

“Moiré Effect” and “Moiré Lens Arrangement”

The moiré effect refers to an apparent coarse raster that is created byoverlaying regular, finer rasters. The resulting pattern, whoseappearance is similar to patterns resulting from interference, is aspecial case of the aliasing effect by subsampling. In the field ofsignal analysis, aliasing effects are errors that occur when the signalto be sampled contains frequency components that are higher than halfthe sampling frequency. In image processing and computer graphics,aliasing effects occur when images are scanned and result in patternsthat are not included in the original image. A moire lens array is aspecial case of an Alvarez lens array.

“Monolithic Construction Element”

A monolithic construction element is a construction element made of onepiece. A typical such device is for example a monolithic pixel array,where the array is made of one piece and the μ-LEDs of the array aremanufactured together on one carrier.

“Optical Mode”

A mode is the description of certain temporally stationary properties ofa wave. The wave is described as the sum of different modes. The modesdiffer in the spatial distribution of the intensity. The shape of themodes is determined by the boundary conditions under which the wavepropagates. The analysis according to vibration modes can be applied toboth standing and continuous waves. For electromagnetic waves, such aslight, laser and radio waves, the following types of modes aredistinguished: TEM or transverse electromagnetic mode, TE or H modes, TMor E modes. TEM or transverse electromagnetic mode: Both the electricand the magnetic field components are always perpendicular to thedirection of propagation. This mode is only propagation-capable ifeither two conductors (equipotential surfaces) insulated from each otherare available, for example in a coaxial cable, or no electricalconductor is available, for example in gas lasers or optical fibers. TEor H modes: Only the electric field component is perpendicular to thedirection of propagation, while the magnetic field component is in thedirection of propagation. TM or E modes: Only the magnetic fieldcomponent is perpendicular to the propagation direction, while theelectric field component points in the propagation direction.

“Optoelectronic Device”

An optoelectronic component is a semiconductor body that generates lightby recombination of charge carriers during operation and emits it. Thelight generated can range from the infrared to the ultraviolet range,with the wavelength depending on various parameters, including thematerial system used and doping. An optoelectronic component is alsocalled a light emitting diode.

For the purpose of this disclosure, the term optoelectronic device oralso light-emitting device is used synonymously. A μ-LED (see there) isthus a special optoelectronic device with regard to its geometry. Indisplays, optoelectronic components are usually monolithic or asindividual components placed on a matrix.

“Passive Matrix Backplane” or “Passive Matrix Carrier Substrate”

A passive matrix display is a matrix display, in which the individualpixels are driven passively (without additional electronic components inthe individual pixels). A light emitting diode of a display can becontrolled by means of integrated circuits (ICs). In contrast, displayswith active pixels driven by transistors are referred to as activematrix displays. A passive matrix carrier substrate is part of a passivematrix display and carries it.

“Photonic Crystal” or “Photonic Structure”

A photonic structure can be a photonic crystal, a quasi-periodic ordeterministically aperiodic photonic structure. The photonic structuregenerates a band structure for photons by a periodic variation of theoptical refractive index. This band structure can comprise a band gap ina certain frequency range. As a result, photons cannot propagate throughthe photonic structure in all spatial directions. In particular,propagation parallel to a surface is often blocked, but perpendicular toit is possible. In this way, the photonic structure or the photoniccrystal determines a propagation in a certain direction. It blocks orreduces this in one direction and thus generates a beam or a bundle ofrays of radiation directed as required into the room or radiation areaprovided for this purpose.

Photonic crystals are photonic structures occurring or created intransparent solids. Photonic crystals are not necessarilycrystalline—their name derives from analogous diffraction and reflectioneffects of X-rays in crystals due to their lattice constants. Thestructure dimensions are equal to or greater than a quarter of thecorresponding wavelength of the photons, i.e. they are in the range offractions of a μm to several μm. They are produced by classicallithography or also by self-organizing processes.

Similar or the same property of a photonic crystal can alternatively beproduced with non-periodic but nevertheless ordered structures. Suchstructures are especially quasiperiodic structures or deterministicallyaperiodic structures. These can be for example spiral photonicarrangements.

In particular, so-called two-dimensional photonic crystals are mentionedhere as examples, which exhibit a periodic variation of the opticalrefractive index in two mutually perpendicular spatial directions,especially in two spatial directions parallel to the light-emittingsurface and perpendicular to each other.

However, there are also one-dimensional photonic structures, especiallyone-dimensional photonic crystals. A one-dimensional photonic crystalexhibits a periodic variation of the refractive index along onedirection. This direction can be parallel to the light exit plane. Dueto the one-dimensional structure, a beam can be formed in a firstspatial direction. Thereby a photonic effect can be achieved alreadywith a few periods in the photonic structure. For example, the photonicstructure can be designed in such a way that the electromagneticradiation is at least approximately collimated with respect to the firstspatial direction. Thus, a collimated beam can be generated at leastwith respect to the first direction in space.

“Pixel”

Pixel, image cell or picture element refers to the individual colorvalues of a digital raster graphic as well as the area elements requiredto capture or display a color value in an image sensor or screen withraster control. A pixel is thus an addressable element in a displaydevice and comprises at least one light-emitting device. A pixel has acertain size and adjacent pixels are separated by a defined distance orpixel space. In displays, especially μ-displays, often three (or in caseof additional redundancy several) subpixels of different color arecombined to one pixel.

“Planar Array”

A planar array is an essentially flat surface. It is often smooth andwithout protruding structures. Roughness of the surface is usually notdesired and does not have the desired functionality. A planar array isfor example a monolithic, planar array with several optoelectroniccomponents.

“Pulse Width Modulation”

Pulse width modulation or PWM is a type of modulation for driving acomponent, in particular a μ-LED. Here the PWM signal controls a switchthat is configured to switch a current through the respective μ-LED onand off so that the μ-LED either emits light or does not emit light.With the PWM, the output provides a square wave signal with a fixedfrequency f. The relative quantity of the switch-on time compared to theswitch-off time during each period T (=1/f) determines the brightness ofthe light emitted by the μ-LED. The longer the switch-on time, thebrighter the light.

“Quantum Well”

A quantum well or quantum well refers to a potential in a band structurein one or more semiconductor materials that restricts the freedom ofmovement of a particle in a spatial dimension (usually in thez-direction). As a result, only one planar region (x, y plane) can beoccupied by charge carriers. The width of the quantum well significantlydetermines the quantum mechanical states that the particles can assumeand leads to the formation of energy levels (sub-bands), i.e. theparticle can only assume discrete (potential) energy values.

“Recombination”

In general, a distinction is made between radiative and nonradiativerecombination. In the latter case, a photon is generated which can leavea component. A non-radiative recombination leads to the generation ofphonons, which heat a component. The ratio of radiative to non-radiativerecombination is a relevant parameter and depends, among other things,on the size of the component. In general, the smaller the component, thesmaller the ratio and non-radiative recombination increases in relationto radiative recombination.

“Refresh Time”

Refresh time is the time after which a cell of a display or similar mustbe rewritten so that it either does not lose the information or therefresh is predetermined by external circumstances.

“Die” or “Light-Emitting Body”

A light-emitting body or also a die is a semiconductor structure whichis separated from a wafer after production on a wafer and which issuitable for generating light after an electrical contact duringoperation. In this context, a die is a semiconductor structure, whichcontains an active layer for light generation.

The die is usually separated after contacting, but can also be processedfurther in the form of arrays.

“Slot Antenna”

A slot antenna is a special type of antenna in which instead ofsurrounding a metallic structure in space with air (as a nonconductor),an interruption of a metallic structure (e.g. a metal plate, awaveguide, etc.) is provided. This interruption causes an emission of anelectromagnetic wave whose wavelength depends on the geometry of theinterruption. The interruption often follows the principle of thedipole, but can theoretically have any other geometry. A slot antennathus comprises a metallic structure with a cavity resonator having alength of the order of magnitude of wavelengths of visible light. Themetallic structure can be located in or surrounded by an insulatingmaterial. Usually, the metallic structure is earthed to set a certainpotential.

“Field of Vision”

Field of view (FOV) refers to the area in the field of view of anoptical device, a sun sensor, the image area of a camera (film orpicking up sensor) or a transparent display within which events orchanges can be perceived and recorded. In particular, a field of view isan area that can be seen by a human being without movement of the eyes.With reference to augmented reality and an apparent object placed infront of the eye, the field of view comprises the area indicated as anumber of degrees of the angle of vision during stable fixation of theeye.

“Subpixels”

A subpixel (approximately “subpixel”) describes the inner structure of apixel. In general, the term subpixel is associated with a higherresolution than can be expected from a single pixel. A pixel can alsoconsist of several smaller subpixels, each of which radiates a singlecolor. The overall color impression of a pixel is created by mixing theindividual subpixels. A subpixel is thus the smallest addressable unitin a display device. A subpixel also comprises a certain size that issmaller than the size of the pixel to which the subpixel is assigned.

“Vertical Light Emitting Diode”

In contrast to the horizontal LED, a vertical LED comprises oneelectrical connection on the front and one on the back of the LED. Oneof the two sides also forms the light emission surface. Vertical LEDsthus comprise contacts that are formed towards two opposite main surfacesides. Accordingly, it is necessary to deposit an electricallyconductive but transparent material so that on the one hand, electricalcontact is ensured and on the other hand, light can pass through.

“Virtual Reality”

Virtual reality, or VR for short, is the representation and simultaneousperception of reality and its physical properties in a real-timecomputer-generated, interactive virtual environment. A virtual realitycan completely replace the real environment of an operator with a fullysimulated environment.

Several aspects relate to the lighting design by suitable projectionunits after the light has left the emitter or μ-LED, i.e. the distancefrom a light source to the eye of a user. In some solutions, the displayis in the line of vision of a user. These solutions are mainly relevantfor automotive and other applications. Alternatively, the virtualelements can be created outside the direct line of sight and their lightmust then be directed to the user's eyes. In all cases, it should beensured that the projection of the image to the user is sufficientlysharp and contrasty. This means that the pixels should be separated fromeach other, so that different raven between two adjacent pixels willcreate the same impression on the user.

In some aspects, a μ-display arrangement or display array will haveoptics to direct light emitted by the μ-LED array in certain spatialdirections or to reduce its divergence, for example, or to allow shapingof a light beam emitted by the μ-LED array. For this purpose, the opticsmay include optical lenses and/or reflectors. The optics may alsoinclude, for example, optical filters to change the color of the emittedlight. Furthermore, the optics may include, for example, lightscattering agents to enable a better homogenization of the emittedlight.

An arrangement with a μ-display may have optics for individual μ-LEDs orcommon optics for some or all μ-LEDs of the μ-LED array, for example todirect light emitted by these μ-LEDs in certain spatial directions or toreduce its divergence or to allow shaping of a light beam emitted by theμ-LEDs. For this purpose, the optics may comprise optical lenses orreflectors, for example. Furthermore, the optics may include, forexample, optical filters or/and light scattering means to change thelight color or the homogeneity of the emitted light for some or allμ-LEDs of the μ-Display. For example, the optics may be arranged on acommon carrier for the μ-LEDs of the μ-LED array.

In another embodiment, an aspect of light guidance is considered whenthe light-emitting display is not in direct line of sight. For thispurpose a light guide arrangement downstream of the light-emittingdevice and having at least two light-emitting devices emitting light ofdifferent colors.

The arrangement also comprises a first and a second elongated lightguide arranged so that light generated by the light emitting devices iscoupled into the light guide. For this purpose, the light guidearrangement further comprises a first coupling element disposed adjacentto the first elongated light guide and configured to couple light of thefirst color into the first elongated light guide. A second couplingelement is disposed adjacent to the elongate second light guide andconfigured to launch the light of the second color into the elongatesecond light guide. Corresponding outcouplings are located at therespective end portions of each of the first and second elongated lightguides. These guide the light to the user's eye. The light guideelements can be made of a transparent material so that they can bearranged in the direct line of sight of the user without impairing theuser's vision. The coupling and decoupling elements can be implementedas separate elements or, for example, as a coating on the correspondinglight guides.

The light emitting device may have a μ-LED display or a μ-LED displaymatrix and the like. These devices can be monolithically integrated. Thesub-pixels of different colors can be integrated on a single device. Asan alternative, a variety of μ-LED displays can be provided, each of theμ-LED displays being adapted to produce light of a specific color. Thegenerated light can then be combined by different optics placed in frontof the μ-LED display. Using different μ-LED displays can reduce thetechnical requirements regarding the size of individual pixels comparedto a solution where sub-pixels of different colors are arranged on thesame substrate. The above solution uses different coupling elements tocouple selectively the light from the light emitting device into thecorresponding light guide. In one aspect, another third coupling elementis provided and positioned opposite the second coupling element. Thethird coupling element is adapted to couple light of a third color intothe elongated second light guide. The different launching element allowsa separate launching of light of a different color into thecorresponding light guide. The separation allows addressing aspects whenlight of different colors or wavelengths is handled. In this respect,light of the third color may have a longer wavelength than the secondcolor.

Depending on the design, light can be generated at a point that isdisplaced or offset in relation to the light guides. Accordingly, lightgenerated by the light-emitting device may have an angle of incidencebetween 30° and 90, in particular between 45° and 90° and in particularbetween 60° and 90, with respect to the surface of the light guide. Inother words, the light is not parallel to the elongated light guide whenit is launched into the guide through the launching element. In someaspects, at least one of the first and second launching elements may belocated on the sidewall of the corresponding elongated light guide. Thedimension of the corresponding launching elements is selected so thatall light from the different pixels of the light-emitting array islaunched.

The first and second elongated light guides can be arranged essentiallyparallel to each other. They may be separated from each other usingspacers between them to provide space for the input and outcouplings.Apart from the input couplers, the end sections of the correspondinglight guides may have an outcoupling. The outcoupling element arrangedon the output section of the elongated first light guide is adapted tocouple out light of the first color. The outcoupling element arranged onthe output part of the elongated second light guide is adapted to coupleout light of the second color. Furthermore, a third outcoupling elementis provided in some variants. The third outcoupling element is locatedon the output part of the elongated second light guide opposite thesecond outcoupling element to couple out light of the third color. Thecorresponding outcoupling elements are arranged in such a way that thelight coupled out by the corresponding outcoupling elements is directedtowards an eye of the user. It is appropriate if some of the outcouplingelements are transparent to light of a different color. For example, thefirst outcoupling element is transparent to light of the second and/orthird color. The second outcoupling element can at least be transparentto light of the third color.

Due to the small size of μ-LEDs, one difficulty for optoelectroniccomponents is to achieve efficient beam extraction. Likewise, the beamshould already be collimated when leaving the device in order to coupleit into an optical device in a suitable way. Due to the small size ofthe individual components on a μ-display, classical lenses placed infront of the individual components are difficult to realize. Therefore,in the following a concept is presented that is based on a curvedemission surface, a foveated display is based on. In addition, a smallimaging error should be achieved.

Starting point of the concept is an illumination arrangement comprisinga light-emitting optoelectronic element and an optical device for beamconversion of the electromagnetic radiation generated by thelight-emitting optoelectronic element, wherein the optoelectronicelement comprises several emission regions arranged in matrix form andeach emission region is assigned a main beam direction.

It was found that the optical device following the light-emittingoptoelectronic element in the beam path can be of simplified design ifat least some and preferably all emission regions of the light-emittingoptoelectronic element are arranged in such a way that their centres lieon a curved surface. In one aspect, this can be achieved with aconcavely curved surface. The center of an emission area is understoodto be the intersection of the main beam direction with the surface ofthe emission area emitting electromagnetic radiation.

In one aspect, the curved surface forms a spherical segment whoseassociated spherical center lies on the optical axis of the opticaldevice. For the preferred concave curved surface for the arrangement ofthe centres of the emission regions, the centre of the sphere is at adistance from the light-emitting optoelectronic element in the directionof the beam path. Alternatively, the curved surface is a rotatingconical section, for example an ellipsoid, paraboloid or hyperboloid.

For a first embodiment, adjacent emission areas are tilted against eachother so that the main radiation directions of the emission areas are atan angle to each other. For a second, alternative embodiment, there areemission areas with a coinciding main beam direction, which are arrangedon different planes with a different distance in the main beam directionto the optical device.

For a further embodiment, it is proposed that the optical device forms asystem optic, in particular an imaging projection optic. By thearrangement of the emission regions an improved compensation of thefield curvature of the system optics is achieved. Additionally, theimaging in the projection optics can be simplified. For a further designof these concepts, several nonplanar collimating optical elements areprovided between the emission areas and the system optics.

In one aspect, each individual emission area forms a separate Lambertianradiator. Furthermore, the emission areas are very small in area andhave maximum edge lengths of less than 70 μm, in particular less than 25μm. For an embodiment of the illumination arrangement, at least one ofthe emission regions is formed by the aperture of a primary opticalelement assigned to a μ-LED or a converter element assigned to a μ-LED.Alternatively, the emission regions can comprise readily collimatingelements, for example in the form of a photonic structure In this case,the emission regions whose centres lie on a curved surface can be partof a monolithic pixelated optochip or they are arranged in severalseparate optochips arranged on a nonplanar IC substrate.

A plurality of different projection units are known in the art, withwhich images can be displayed in specifically defined image planesaccording to requirements. Such projection units are used in so-calledaugmented reality or virtual reality glasses or in head-up displays, forexample in motor vehicles. In the aforementioned special applications ofprojection units, augmented reality applications and head-up displaysregularly display enlarged images at a distance from the viewer. Incontrast, in virtual reality glasses, the projection optics usually takeover the function of a magnifying glass that enlarges the display.

In this context, display units for motor vehicles are known from EP 1544 660 and DE 197 51 649 A1. The latter uses an intermediate image on aground glass screen in order to display the image on the windscreen tothe correct side for the driver by means of additional optics. In thisway, it is possible to display instruments, warning displays or otherinformation important to the driver directly in the field of vision, sothat he can see the information without having to look away from theroad ahead.

An alternative embodiment to transfer images to or into the eye of auser is achieved by so-called light field displays, also known asvirtual retinal display (VNA). In contrast to normal displays, whichcreate an image on a plane directly in front of the user's eye, lightfield displays create an image inside the eye by direct retinalprojection.

The requirement for a light field display of small size and light weightto achieve a comfortably portable system is contrary to the desire toachieve a large field of view with high resolution. Up to now,arrangements with μ-displays as image generators and these imagingmulti-channel optics have been proposed, which split the beam path forreshaping and reunite it on the retina. A suitable system with hybriddiffractive-refractive optics and free-form lenses is described byMarina Buljan, et al., “Ultra-compact multichannel freeform optics for4×WUXGA OLED microdisplays”, Proc. SPIE 10676, Digital Optics forImmersive Displays, 1067607 (21 May 2018).

Other projection units are also known whose pixels emit light that ismixed from light of different colors. In these solutions, light isgenerated spatially separated and then mixed by suitable opticalelements, such as an achromatic lens, and combined into a beam. In thecase of displays that generate color by means of pixels arranged in amatrix on a surface, the light must be sufficiently collimated to beable to resolve adjacent pixels of different colors, especially at highfill factors.

In contrast, other solutions suggest using μ-LEDs with a low packingdensity. However, this leads to significant differences betweenpunctually illuminated and dark areas when viewing a single pixel area.This so-called fly screen effect (screen door effect) is particularlynoticeable at a short viewing distance and thus especially inapplications such as AR or VR glasses.

Other solutions with adaptive optics for phase modulation and beamshaping are mentioned by Jonathan D. Waldern, “DigiLens switchable Bragggrating waveguide optics for augmented reality applications”, Proc. SPIE10676, Digital Optics for Immersive Displays, 106760G (21 May 2018).Waveguides are proposed for HMDs with integrated diffractive opticalelements (DOE) formed by switchable Bragg gratings (SBG). To produce theSBGs, liquid crystals are embedded in a polymer. Prior topolymerization, pattern-forming cavities are created by holographicprocesses to accommodate the liquid crystal phase in the monomerstarting material. After solidification of the matrix, the liquidcrystals can be aligned by means of an electric field so that avariation of the refractive index results in a switchable beamdeflection.

An alternative adjustment optics for VR HMDs is described by R. E.Stevens, et al., “Varifocal technologies providing Prescription and VACmitigation in HMDs using Alvarez Lenses”, Proc. SPIE 10676, DigitalOptics for Immersive Displays, 106760J (21 May 2018). The disclosureconcerns the use of Alvarez lens pairs to adjust the beam path of videoglasses.

Based on the known problems, further solutions will be proposed. It isconsidered to be not insignificant that the optics used for beamguidance and beam shaping are as efficient as possible so that opticallosses are considerably minimized.

One aspect thus concerns a projection unit comprising an optoelectroniclighting device and projection optics, the optoelectronic lightingdevice comprising a matrix of pixels for the emission of visible light.Each pixel comprises several μ-LEDs with spectrally different lightemission so that sub-pixels of different colors are formed. Each μ-LEDis separately controllable and may be connected to the driver circuitsdisclosed in this application. The matrix of pixels comprises in someaspects one or more μ-LED modules having the structures disclosed inthis application. For example, the matrix may comprise an antennastructure or a bar shape as disclosed herein. Various measures such as atransparent cover electrode, photonic structure or similar may beprovided to improve outcoupling and directionality. In oneconfiguration, the matrix can be formed by pixel modules (each withthree subpixels) attached to a carrier substrate. The carrier substratemay contain leads and drive circuits and may be made of a differentmaterial system than the matrix.

In addition, each pixel is assigned a separate collimation optics, whichis connected upstream of the projection optics to increase the fillfactor. According to the invention, the collimation optics areconfigured in such a way that enlarged and overlapping intermediateimages of the μ-LEDs of the respective pixel are generated in the beampath in front of the projection optics. Accordingly, the collimationoptics assigned to each individual pixel not only increases the degreeof illumination of a pixel, but additionally enables a spatialcorrection of the radiation of the μ-LEDs forming subpixels by means ofthe most accurate possible superimposition of the subpixel intermediateimages, which enables efficient light coupling into the projectionoptics following in the beam path. It should be mentioned at this pointthat such an optic would be suitable for the concepts presented here,which provide partly redundant subpixel elements.

It is advisable to adapt the collimation optics in such a way that thedegree of overlap of the intermediate images of the μ-LEDs belonging tothe same pixel is as high as possible. An overlapping of theintermediate images of the Hμ-LEDs of a pixel of at least 85% andfurther of at least 95% of their intermediate image area has proven tobe suitable.

Furthermore, an embodiment is preferred for which the intermediateimages of the μ-LEDs are virtual intermediate images. In an aspect, thecollimation optics generate a virtual image of the subpixels, so thatthe size of the virtual image of a subpixel corresponds to the size ofthe pixel. Furthermore, the collimation optics is preferably arrangedbetween the μ-LEDs of a pixel and the projection optics.

The light emitted by μ-LEDs with different colors can occupy areas ofthe pixel of equal size or the areas occupied by the subpixels areadapted to the light emission and are of different sizes. For anembodiment, it is intended that the subpixel emitting green lightoccupies the largest surface area of the pixel compared to the other twosubpixels or at least that green light is emitted over a larger area.This is due to the fact that the eye is most sensitive to the greencolor. Furthermore, it is useful if the surface area of an RGB pixeloccupied by subpixels for red light is larger than the surface areaoccupied by subpixels emitting blue light. According to this embodiment,green light is emitted over a larger surface area of the pixel than redlight, and red light is emitted over a larger surface area of the pixelthan blue light. By means of the proposed collimation optics of thepixel, intermediate images are generated by the differently sized anddifferently located μ-LEDs of the subpixels in the beam path in front ofthe projection optics, which have a high degree of overlap.

According to another aspect, small μ-LEDs are used so that there arelarge surface areas in the individual pixels that do not emit light.Preferably, the semiconductor lighting devices of a pixel occupy no morethan 30% and moor preferably no more than 15%, most preferably no morethan 10% of the pixel area. This ensures that optical and electricalcrosstalk between the individual pixels is prevented. Preferably, thesub-pixels are arranged in such a way that they are not directly on theedge of a pixel and do not adjoin each other. In addition to μ-LEDs, theterm μ-LEDs also includes color converted μ-LEDs or VCSELs with suchedge length or μ-LEDs illuminated optical fiber end pieces. The slottedantenna structures that would be regarded as such μ-LEDs should also bementioned at this point.

The collimation optics assigned to each pixel offers the advantage thatthe light emitted by the subpixels is converted into a pre-collimatedbeam, which is then available in an advantageous way for the generationof an image by at least one further optical element. By using at leastone suitable collimating optical element, pre-collimated light beams canthus be generated, so that in turn optical crosstalk between theindividual light beams emitted by the subpixels is prevented or at leastreduced.

An aspect provides that the collimation optics comprises at least oneholographic optical element (HOE) that compensates for the differentpositions of the three semiconductor lighting devices on the surface ofthe pixel. Alternatively or in addition, it is conceivable that thisfunction is achieved by a refractive optical element (ROE), which is acomponent of the collimation optics. It is also conceivable that adiffractive optical element (DOE) is used as a supplement or alternativeto achieve appropriate compensation of the different positions of thesemiconductor luminous devices on the illuminated area in theintermediate image of the pixel.

In further aspects, the projection unit will be adapted further. In onedesign it comprises a projection optic which is arranged downstream ofthe collimation optic in the beam path. With the help of the projectionoptics, an image or another intermediate image is generated from theindividual intermediate images generated by the collimation optics. Thisimage or intermediate image is used directly or in further processedform to display the desired information to the viewer. For this purpose,the projection optics has suitable optical elements, such as deflectionmirrors, beam splitters and/or lenses, which are preferably controlledby a control unit and can be moved in such a way as to effect beamsteering and/or beam deformation as required, so that information ispresented in an easily understandable and perceptible form on a display,on a matt screen and/or as a virtual image, for example in front of thewindscreen of a motor vehicle.

A proposed projection unit, according to at least one of the previouslydescribed aspects, can be used to generate an image for an augmentedreality application, for a virtual reality application, and/or in ahead-up display. In particular, the proposed one can be installed in anaugmented reality spectacle and/or in a virtual reality spectacle wornon the head by the viewer.

In addition to directing light to a display and creating a virtualimage, there is another way of transmitting information to the user. Itis based on the knowledge that the eye does not have a uniformresolution over its range of perception. Rather, the eye has a very highspatial and also color vision in the area of its fovea centralis.However, this decreases at larger angles, so that in the area ofperipheral vision, i.e. at approx. 20° to 30°, both spatial resolutionand color vision decrease. In conventional displays, this is not takeninto account further, i.e. the number and size of the individual pixelsis substantially constant over the entire row or all columns.

The fovea centralis, also known as the visual fossa, is a sunken area inthe centre of the yellow spot on the retina with a diameter of about 1.5mm in an adult person. It is characterised by a high surface density oflight receptors, which also have a direct neural connection. The foveacentralis has only cones for daylight vision, with predominantly M conesfor the green spectrum and L cones for red light.

This application discloses novel concepts with which the differentresolution capabilities of the eye is considered. This includes thegeneration of different resolutions by suitable optics as well as asolution with variable pixel density.

In the following concept, an approach is to be pursued in which a lightguiding arrangement is provided that takes into account the resolutioncapability on the retina of the eye, thus reducing the requirements fora μ-display with respect to pixel density and size.

The proposed light guiding arrangement here comprises at least oneoptoelectronic imaging device, in particular a μ-display for generatingat least a first image and a second image. Furthermore, at least oneimaging optic is provided which is configured to project a first imageof the first image with a first resolution onto a first region of theretina of an eye of the user and to project a second image of the secondimage with a second resolution onto another, second region of theretina, the first resolution being different from the second resolution.

The first image and the second image can be a respective image of asequence or sequence of images. In particular, the images may be atleast two successive images of a sequence or succession of images, whichare perceived by the user as a scene or frame, the individual imagesnormally being displayed so quickly that the eye does not perceive themas individual images but only as a scene or frame in their entirety. Inthis case, the first image can have a first partial image with the firstresolution and the second image can have a second partial image with thesecond resolution. Thus, in the eye of the user, the first and thesecond image each have different resolutions.

With the proposed light guiding arrangement, the first image with thefirst resolution can be projected onto the first region of the retinaand the second image with the second resolution onto the second regionof the retina. Different areas of the retina can thus be illuminatedwith images whose resolutions are adapted to the physiologicalpossibilities of the retina. For example, an image can be projected ontoan outer area of the retina with a relatively low resolution, whileanother image is projected onto a central area of the retina with ahigher resolution.

The proposed light guiding arrangement therefore allows differentresolutions of the projected images to be provided for different regionsof the retina, so that resolutions can be achieved that lead to pixelsthat are no longer resolvable for the eye. On the other hand, so-calledoversampling can be avoided, since, for example, the resolution at anypoint of the retina can be adapted to the actual receptor density of theretina. Thus, it is possible to execute an optoelectronic imager moreeasily, since it does not have to deliver high resolution imageseverywhere.

In particular, an image of an image cannot be generated with constantresolution over the entire surface of the retina. Rather, it is takeninto account that the resolving power of the eye is lower in theperipheral areas of the retina than in the centre. This is particularlyadvantageous compared to a system that produces an image with constantresolution over the entire surface of the retina. In this case, aconstant pixel density is provided, so that either the resolution in theperipheral areas of the field of view is higher than the eye canperceive, or the resolution in the centre of the retina is too low toenable good image perception.

With regard to the regions into which a respective image is projected,in particular for a respective frame, a so-called scanning method can beused, in which, in particular to generate a respective overall image orframe, the entire retina is gradually scanned. The areas, such as inparticular the first and second region, are therefore smaller than thetotal area of the retina.

It may also be intended that at least one image for a frame, especiallythe first or second image, fills the entire surface of the retina. Atleast one region, such as the first region or the second region, maytherefore correspond to the total area of the retina.

The imaging optics or components thereof and the imaging device may besynchronized in such a way as to produce at least one frame comprisingthe first and second images, which the eye perceives as a completeimage. It is understood that the retina, the eye and the user are notpart of the optoelectronic device.

The first and second images generated by the at least one imaging deviceor μ-display may have a total number of pixels projected onto the firstand second areas of the retina where they appear as first and secondimages, respectively. The resolution of the first and second image istherefore determined by the ratio of the number of pixels and the areaof the area into which the respective image is projected on the retina.Each image can be assigned a resolution with which the image isprojected onto the respective area of the retina.

The images generated by the at least one imaging device have the sameresolution according to the number of pixels of the respective imagingdevice when leaving the imaging device and only when the image isenlarged or reduced by the imaging optics does the resolution of therespective projected images on the retina differ.

Compared to a conventional projection of an image generated by animaging device such as DLP or LCD over the entire retina, thelight-guiding device based on this concept can enable a frame of severalnon-resolvable images with different resolutions according to thesensitivity of the eye to be projected onto the retina using a morecompact component than an imaging device or with fewer pixels or asmaller imaging device diagonal, without limiting the visual experience.

Such a frame, which is composed of images, can also be called a scene,where the images can be projected onto the retina of the eyesimultaneously or sequentially. A scene with sequentially displayedimages is usually so fast that the eye perceives them as a singleoverall image. Typical refresh rates are 60 or 120 Hz and the displayduration per image is a fraction of a frame, with 2 to 100 images,preferably 5 to 50 images, being displayed per frame.

The imaging device, for example in the form of a μ-display, can beconfigured to comprise a pixel size with dimensions in the range of afew μm, in the range of 100 μm×100 μm or less. Such pixel sizes can berealized with displays that include μ-LEDs. Distances between two pixelscan be in the range of about 1 μm to 5 μm, the pixel size itself issmaller than 70 μm and can for example be smaller than 20 μm or in therange of 3 μm to 10 μm.

Alternatively, such pixel sizes can be realized with displays based on amonolithic, pixelated array. Therefore, the imaging device can beadapted as a monolithic component, but the individual pixels can beindividually controlled. The array can be an RGB array. Separate arraysfor each color, especially RGB color, can also be provided. The pixelscan, for example, have sizes in the range of a few μm to a maximum of 50μm and be almost seamlessly adjacent to each other. With such imagingdevices, the number of pixels can be in the range 1000 to 50000, wherebythe pixels are preferably directly adjacent. The use of monolithicpicture generator allows compact components to be realized.

The at least one optoelectronic imager may be formed by an array ofμ-LEDs with m×n pixels. m and n may have values between 50 and 5000inclusive, preferably between 100 and 1000 inclusive. The size of thepixels and the distance between adjacent pixels (pitch) may be constant.Typical values for the pitch can be in the range between 1 μm and 70 μminclusive, preferably between 2 μm and 30 μm inclusive, and particularlypreferably between 2 μm and 10 μm inclusive.

The at least one optoelectronic imager may have subpixels with at leastone primary color, but preferably subpixels with the three primarycolors red, green and blue (R,G,B). Subpixels of all three primarycolors form one pixel. The number or the density per area of thesubpixels can be different. For example, several green subpixels may beprovided because the eye is sensitive especially in the green area.

The antenna structure proposed in this application is also conceivable.Likewise, μ-rods as disclosed herein or optoelectronic elements withdyes in between would also be possible. With μLEDS the distances betweenpixels could also be greater. For example, arrangements are possible inwhich the distance between adjacent pixels is between 1 and 5 times thepixel size. Such shapes and designs are disclosed in this application.

With the help of such a display it is possible to project an image witha high resolution onto the entire image area of the retina. However,this places high demands on the production and integration of suchdisplays, especially if resolutions in the HD range (1920×1080 pixels)are to be achieved. The light guiding arrangement according to theinvention allows the use of such high-resolution displays as imagegenerators. However, lower resolution image generators can also be used,since—as already explained—a higher resolution can be achieved on theretina.

The first region in which the first, especially higher resolution isachieved may be located in the center or closer to the center of theretina than the second region in which the second, especially lowerresolution is achieved. The higher first resolution takes into accountthe higher receptor density in the center of the retina.

The first and second regions can be arranged on the retina so that thesecond region concentrically surrounds the first region. Accordingly,the first region in the center of the retina has the shape of a circle,for example. This can be surrounded concentrically by at least onesecond region, for example in the shape of a ring. The individual imagescan thus enclose themselves on the retina like concentric circles,whereby a partial overlap is also possible.

The imaging optics may include a beam steering device, which directslight rays of the first image onto the first region of the retina toproduce the first image and light rays of the second image onto thesecond region of the retina to produce the second image. By means of thebeam steering device, images produced by an imager can be projected ontothe respective intended retinal regions. A control system may beprovided which controls the beam steering device in dependence on animage displayed by the imager.

The beam steering device may have at least one movable and/or fixedmirror or other equivalent reflecting element to direct the beam. Themovable mirror may, for example, be configured to tilt about one, two,three or more axes, preferably about one or two axes. The control systemcan control the positioning of the mirror in dependence on an imagedisplayed by the imager.

The beam steering device may have at least one, and preferably at leasttwo, optical fibres for beam steering. The glass fibres may be fixed.Depending on the image, the light beams emitted by an imaging device canbe coupled into different glass fibres. Each glass fibre can illuminatea specific, assigned area of the retina. The image of an image thereforeappears on the area of the retina that is assigned to the glass fiberinto which the light rays are coupled to form the image.

The imaging optics may have at least one beam-shaping device, whichfocuses the light rays of the first and second images on the respectivearea of the retina. The light rays of the first image can be focusedmore strongly than the light rays of the second image. The first imageresulting from the first image on the retina thus appears on a smallerarea than the less strongly focused second image. The first imagetherefore has a higher resolution than the second image.

The beam shaping device may have at least one focusing or magnifyingoptic, at least two different magnifications may be provided, preferablybetween three and ten different magnifications. The highest and lowestmagnifications of the beam shaping device may differ, for example, by afactor between 1.1 and 10, preferably between 1.5 and 5, particularlypreferably between 1.8 and 3. The imaging optics may have at least afirst beam-shaping element and a second beam-shaping element. The firstbeam shaping element can focus the light beams of the first image andthe second beam shaping element can focus the light beams of the secondimage.

The at least one first and one second beam-shaping element can beformed, for example, from a lens, in particular a converging lens and/ora diverging lens. It is also possible for the at least one first andsecond beam-shaping element to be formed from a segmented lens which mayhave a plurality of smaller converging lenses and/or diverging lenses.In addition to lenses of classical design, other suitable opticalelements, for example flat optical elements, can also be used asbeam-shaping elements, for example metal lenses.

The at least one first and one second image can be displayed one afterthe other, especially on the same image generator. A composite overallimage resulting therefrom for the eye can be produced on the retina by ascanning process, since different areas of the retina can be illuminatedat different times. In doing so, the retina can be at leastsubstantially completely illuminated within a scene comprising at leastthe first and the second image or image.

The first and the second image can be displayed at least substantiallysimultaneously, in particular on at least two different imaging devices.Thus, a simultaneous projection of the first image and the second imageonto the corresponding areas of the retina can be performed. For thispurpose, the first and the second image are generated at leastsubstantially simultaneously on different imaging devices and aprojection can be made on the intended retinal areas by means of arespective, assigned beam steering device. The advantage of this is thatthe beam steering devices can be easily designed, as there are no movingparts, for example. In addition, by mapping the images from severalimaging devices onto assigned retinal areas, an adapted resolution canbe easily achieved on each area of the retina.

The optoelectronic device may have at least one controller designed tocontrol the imaging optics in dependence on a respective image providedby the imager.

An alternative way of transferring images to or into the eye of a useris achieved by so-called light field displays, also known as virtualretinal displays (VNA). In contrast to normal displays, which create animage on a plane directly in front of the user's eye, light fielddisplays create an image inside the eye by direct retinal projection.

Rather, the concepts presented here propose a light field displaycomprising an optoelectronic device for generating a raster image and anoptics module for direct retinal projection of the raster image into auser's eye. In order to improve the image resolution while maintaining acompact size, the proposed operating method is based on the realizationthat in addition to a first raster image projected flat onto the retinaof a user, a second raster image, which has a higher resolution and asmaller spatial extent than the first raster image, is imaged onto thefovea centralis in the user's eye.

The projection covers at least the fovea centralis and can draw apicture on a further area around the fovea centralis, which is assignedto the parafovea. This ensures that a certain centering error of thesecond raster image relative to the position of the fovea centralis isnot perceived in the user's eye. A maximum diameter of the secondpartial raster image projected onto the retina of 5 mm, preferably of 4mm and especially preferably of 3 mm is advisable.

In some aspects of the proposed concept, the light field displaycomprises a first imaging unit generating a first raster subimage and asecond imaging unit generating a second raster subimage. The rasterimage projected onto the retina comprises the first raster sub-image andthe second raster sub-image. Thus, there may be additional rastersub-images that are projected onto different areas of the retina with anadapted resolution. It is possible to create configurations for whichthe retinal projections of the raster images overlap.

For an embodiment, the retina-projected raster image is composed of thefirst raster sub-image and the second raster sub-image, whereby thefirst raster sub-image has a dark area in the area of the foveacentralis, into which the second raster sub-image is faded in withhigher resolution by an adjustment optic. The adjustment optic isconfigured in such a way that the relative position of the retinalprojection of the second raster subimage can be adjusted in relation tothe retinal projection of the first raster sub-image. For this purpose,an advantageous embodiment of the adjustment optics has a switchableBragg grating. For a further embodiment according to some aspects, theadjustment optic includes an Alvarez lens arrangement, in particular arotatable version with a Moire lens arrangement. Here, the beamdeflection is determined by the first derivative of the respective phaseplate relief, which is approximated, for example, by z=ax2+by2+cx+dy+efor the transmission direction z and the transverse directions x and y,and by the offset of the two phase plates arranged in pairs in thetransverse directions x and y. For further design alternatives,swiveling prisms or other elements with the same functionality areprovided in the adjustment optics.

For a further embodiment, the optical module of the light field displayhas collimation optics for the first imaging unit and/or the secondimaging unit. Preferably, the adjustment optics are at least partiallyarranged in the collimation optics and especially preferably completelyin the collimation optics. In some aspects, an adjustment optics can beat least partially located between the collimation optics and awaveguide. Particularly, flat embodiments use an adjustment optic, whichis at least partially arranged, in a waveguide or completely in thewaveguide.

For the light field display according to the proposed principle, thefirst imaging unit and/or the second imaging unit are formed by a lightemitting diode microarray. This has the advantage that a space-savingarrangement results, since the μ-LED module and/or a μ-display for theparticularly high resolution and its control components can be designedin a small construction due to the limited projection area. For anembodiment, the μ-LED module for the second imaging unit can besimplified in terms of design by the fact that at least the centralareas have pixels that generate light only in the green and red spectralrange, which can be detected by the cones of the fovea centralis.

For an embodiment, the light field display is assigned in some furtheraspects to a measuring device for determining the position of the foveacentralis in the user's eye. This may include an IR illumination devicefor measuring the retina. In particular, a device may be provided whichdetermines the position of the fovea centralis by an imaging procedure.It is also possible to determine the position indirectly by measuringthe optical axis of the eye on the basis of the pupil position or bydetecting the location of the more visible optic nerve papilla on theretina. From the centre of the optic nerve papilla, the centre of thefovea centralis in the average adult is at a transverse distance of 4.5mm (15°) laterally (on the temporal side) and a vertical offset of 0.65mm (2° 10′) proximally.

For a further configuration of the light field display, the projectionof the first raster sub-image onto the fovea centralis is dynamicallytracked and thus follows the direction of the user's gaze. For thispurpose, an eye movement detection device and a control device for theadjustment optics are provided. For possible designs, the eye movementdetection device has an imaging measuring device for the fovea centralisor another reference point in the eye, such as the pupil axis or theoptic nerve papilla. In addition, the control device may also have aprediction device which has a model of the eye movement stored in it andwhich additionally processes the superimposed image data. In doing so,moving objects in the image to which the user most probably directs thedirection of gaze can be detected and this information can be fed intothe motion model.

Another concept is based on the fact that the human eye does not seeequally well everywhere in its full range of vision, both in terms ofcolor perception and spatial resolution. In particular, eye sensitivityvaries across the visual range, so that good spatial resolution and goodcolor resolution are only necessary in the area around the center of aμ-display. Thus, power consumption can be reduced compared toconventional displays or pixel arrays. In addition, a more compactcomponent can be implemented without restricting the visual experience.

Thus, an imaging element only needs to have as good a resolution as isrequired for the respective areas in the eye.

The application now suggests to create a imaging element with a variablepixel density and to generate the image by scanning with a suitableoptical system. For example, the imaging element comprises a linearimaging element with variable pixel density and suitable optics so thatthe actual image is generated by scanning the polar angle. Optics areused to “rotate” an image strip represented by a line array, resultingin a circular two-dimensional image with a variable pixel resolution foran user. This resolution decreases with increasing distance from thecentre according to the sensitivity of the eye. The linear imagingelement can be, for example, an array of μ-LEDs or a monolithicpixelated RGB array. The latter is a monolithic component in whichindividual areas can be individually controlled. The versions of μ-LEDsor modules disclosed in this application are particularly suitable forsuch an arrangement. The size of the μ-LEDs or pixels should be as smallas possible in the centre of the visual range of the eye to achieve highresolution. In the peripheral areas, a much coarser resolution is thensufficient, since the sensitivity of the eye is also lower here. Here,the color reproduction can also be greatly reduced and in extreme casescan be limited to green light only, since the color perception of theeye is also greatly restricted in the peripheral areas.

In some aspects, a pixel array is proposed, especially for a display inpolar coordinates. This comprises a plurality of pixel elements arrangedin at least one row from a starting point on an axis through thestarting point. The plurality of pixel elements each have a height and awidth. At least the width of the pixels, defined as the distance betweenthe centers of two adjacent pixels, is variable in such a way that thewidth of the pixel elements increases along the row from the startingpoint. In other words, the individual pixel elements become wider thefurther away they are from the defined starting point. This line, in aconfiguration also two or more lines on top of each other, can be usedto display a display. In this context, the term “pixel” refers to anaddressable picture element of a predefined size, which includes atleast one light source. The light source can be of the same size as thepixel, but can also be smaller. Thus, the increase in width can beachieved by different active areas of the light source in the pixel orby increasing dilution. In other words, with increasing distance, thepredefined size becomes larger while the light area remains the same, orthe light-emitting area becomes smaller while the predefined sizeremains the same.

In one aspect, not only the width but also the height can be variable.For example, the pixels can also have a variable height, which increaseswith increasing distance from the starting point.

It may be intended to rotate the light coming from the row array (whichforms a light strip) so that a light strip rotating around the startingpoint results. If this rotation is sufficiently fast, the result is asubstantially circular display. The focal point of the eye issubstantially in the starting point, which is also the point ofrotation. In a design, the variable height is chosen so that theposition of the pixel elements from one position to the next areadjacent to each other due to the rotation of the light strip.

In an aspect, the starting point forms a central midpoint and the manypixel elements are arranged symmetrically around the midpoint along theaxis in one row. This configuration is similar to the design mentionedabove. The only difference is that the rotation is no longer 360°, butonly 180° to create a complete image. This allows higher frame rates tobe achieved at the same rotation frequency. Alternatively, the opticalsystem can be simplified, since it only has to rotate in a reducedangular range.

In another aspect, the array contains pixels of several basic colors, sothat a multi-colored display can be realized. This is done either by analternating arrangement of the colors within the same one row or thearray comprises further rows above and/or below the primary line, whichcontain pixels of other primary colors. A colored pixel can also beformed by one subpixel, in which case three subpixels of different colorare combined to one pixel. This is the conventional approach forμ-displays. In the present case, however, due to the different lightgeneration and guidance concept, for the sake of simplicity, pixels andsubpixels are used synonymously.

Another aspect concerns the different color perception of the eye, whichchanges depending on the position as well as the spatial resolution. Ingeneral, this aspect can be realized in different ways. In anembodiment, for example, two adjacent pixels in a row have a differentcolor. Thus, the plurality of pixel elements can include at least threedifferent colors, with the number of pixels (or subpixels) of therespective color being different. For example, these can be the colorsgreen, red, blue, and yellow. To take into account the decreasing colorsensitivity of the eye, the number of pixels of different color can alsovary with increasing distance. For example, pixels of the color greenmay occur more frequently with increasing distance from the startingpoint than corresponding pixels of other colors.

This generally varies the color distribution of the large number ofpixels along the axis. For example, the colors in the central area, i.e.near the starting point, are evenly distributed, and further outwardsthe color to which the eye is still sensitive dominates.

In an alternative configuration, a first number of the plurality ofpixel elements is arranged in a first row, a second number of pixelelements is arranged in at least one second row. The pixels in the firstrow differ in color from pixels in the second row. There may be three orfour rows of pixel elements, with the pixels in each row being of adifferent color.

It may also be provided that each of the at least two rows containspixel elements of all colors. However, these are arranged differentlyfrom row to row, so that the nth pixel of each row differs in color.This can be useful when creating an overall image by rotating the rows.

In an embodiment, the rows are arranged essentially parallel to an axis.In an aspect, a first row of the at least two rows is arranged centrallyon the axis, a second row then follows below the centrally arranged row,a further row eventually above. However, it is also possible to placeall rows in a common starting point and at a defined angle to eachother. In this way, each row is arranged along an axis, but notparallel. For example, three rows can have a common starting point andinclude an angle of 60°.

Some other aspects concern a distribution of pixels of different colors.The first and at least one second row need not have the same number ofpixels. For example, the first number of the plurality of pixel elementsin the first row is different from the second number of the plurality ofpixel elements in the at least one second row. For example, the activearea of the light source may be different in the pixels of the first rowand the pixels of the second row. This aspect can be realized mainly ina range of the rows, i.e. from a predefined distance from the startingpoint depending on the sensitivity of the eye.

In particular, one aspect requires that at least some pixels of thefirst and second row have the same width and from an n-th pixel of thefirst row on the width is different from the width of the n-th pixel ofthe second row. In an embodiment, the one row or the several rows isdesigned as a pixelated array, in which each pixel of the array can becontrolled individually. Such an array can be configured as a monolithiccomponent. Alternatively, the individual pixel elements can beimplemented by μ-LED.

Another aspect concerns a pixel matrix. As described above, to form adisplay and an image, it is sufficient to use a pixel array and torotate the light strip generated by this array. In aspects, a pixelarray with at least two pixel arrays is now also proposed, especiallyfor a display in polar coordinates. The at least two pixel arrays have acommon center, i.e. their respective starting point is the same.Furthermore, the two pixel arrays form a defined angle to each other.For example, the angle between the pixel arrays is 90° for two pixelarrays, for three pixel arrays the angle can be 60°.

Another aspect concerns a display arrangement in polar coordinates. Suchan arrangement comprises a pixel array or matrix and an optical systemfor light deflection and rotation of the light strip generated by thepixel array during operation. The optical system comprises a mirror,which is movable about at least two axes, which is arranged in a mainradiation direction of the pixel array or the pixel matrix and isadapted to make radiated light from the pixels arranged in row rotateabout a point corresponding to the starting point.

Finally, a last aspect concerns a method for operating a pixel array ora pixel matrix. For this purpose, a first light strip with a pluralityof pixel elements arranged in a row is generated and this light strip isguided to a target location. Then a second light strip is generated. Thesecond light strip is rotated by a certain angle and a rotation point,whereby the rotation point corresponds to the starting point of thepixel elements arranged in a row. The second light strip thus rotated isthen guided to the target location. In an embodiment, the rotation ofthe light strip takes place via one or more mirrors. The row can be asingle or several rows. A monolithically integrated pixelated componentcan also be used as such a row.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following section, some of the above-mentioned and summarizedaspects are explained in more detail using various explanations andexamples.

FIG. 1A shows a diagram illustrating some requirements for so-calledμ-displays or micro-displays of different sizes with respect to thefield of view and pixel pitch of the μ-display;

FIG. 1B shows a diagram of the spatial distribution of rods and cones inthe human eye;

FIG. 1C shows a diagram of the perceptual capacity of the human eye withassigned projection areas;

FIG. 1D is a figure showing the sensitivity of the rods and cones overthe wavelength;

FIG. 2A is a diagram illustrating some requirements for microdisplays ofdifferent sizes in terms of the field of view and the angle ofcollimation of a pixel of the μ-display;

FIG. 2B illustrates an exemplary execution of a pixel arrangement toillustrate the parameters used in FIGS. 1A and 2A;

FIG. 3A shows a diagram illustrating the number of pixels requireddepending on the field of view for a specific resolution;

FIGS. 3B-1 and 3B-2 are a table of preferred applications for μ-LEDarrays;

FIG. 4A shows a principle representation of a μ-LED display withessential elements for light generation and light guidance;

FIG. 4B shows a schematic representation of a μ-LED array with similarμ-LEDs;

FIG. 4C is a schematic representation of a μ-LED array with μ-LEDs ofdifferent light colors;

FIG. 5 is an example of a pair of glasses for advanced realityfunctionality that uses a μ-display to illustrate various aspects andbasic principles;

FIG. 6 shows a first embodiment of a light guiding concept of a curvedlight surface according to some aspects of the proposed concept;

FIG. 7 shows an enlarged partial view for the embodiment of the lightguide concept with separate μ-LEDs on a non-planar IC substrate;

FIG. 8 represents a third embodiment of a light guide with a monolithicpixelated chip according to further aspects;

FIG. 9 shows a fourth embodiment of a lighting system with some aspects;

FIG. 10 is a further development of one of the above embodimentaccording to some aspects of the concept presented;

FIG. 11 is another embodiment of the example of FIG. 7, with additionallight-shaping structures;

FIG. 12 is a supplement to the embodiment of FIG. 10, where a photonicstructure is arranged in the beam path;

FIG. 13 shows a further embodiment based on the example in FIG. 9;

FIG. 14A shows a further embodiment based on the example in FIG. 9;

FIG. 14B shows a top view of an embodiment of a step-shaped substrate;

FIG. 15 is an embodiment with a reflective circumferential structurearound the optochip;

FIG. 16 combines nanorods arranged on its curved surface of a substratewith control;

FIG. 17A shows a matrix with RGB pixels, which has a high fill factor;

FIG. 17B is a schematic representation of the beam guidance in aconventional projection unit;

FIG. 18 shows an embodiment of an implemented matrix with RGB pixels,which has a small fill factor according to some aspects of the proposedconcept;

FIGS. 19A and 19B show a top view and a cross-sectional view of acombined embodiment with features of the embodiment examples of FIG. 18;

FIGS. 20A and 20B show top views of further versions of a matrix withRGB pixels, realized by μ-LED arrangements according to some of theconcepts presented here;

FIG. 21 shows another embodiment of an executed matrix with RGB pixels,which has a small fill factor according to some aspects;

FIG. 22 illustrates a top view of an embodiment of a matrix with alight-shaping structure arranged on it;

FIG. 23 shows a schematic representation of a projection unit accordingto some aspects of the proposed principle;

FIG. 24 shows a schematic representation of the generation of anintermediate image by the projection unit of the previous figure;

FIG. 25 shows the chromatic phase function of the collimation optics ofFIG. 23;

FIG. 26 shows a metal lens of collimating optics according to someembodiments of the proposed concept;

FIG. 27 shows a schematic side view of a monolithic array with severalintegrated μ-LEDs to illustrate some aspects of the proposed concept;

FIG. 28 shows an example of an arrangement for beam guidance accordingto some aspects of the presented concept, which takes into account thedifferent spatial resolution of the eye;

FIG. 29 are schematic illustrations for a beamline device in thearrangement of the previous figure;

FIG. 30 shows another embodiment of a beamline arrangement to explainfurther aspects of the concept presented;

FIG. 31 is a further embodiment of an arrangement for beam guidance thattakes into account the different resolving power of the human eye;

FIG. 32 shows a representation of a μ-display for the applicationillustrated in FIG. 30;

FIG. 33A illustrates different possibilities of a μ-display forgenerating light in a beam guiding device according to the proposedconcept FIG. 33B is another possibility to combine a beam deliverydevice with a μ-display embodiment;

FIG. 33C shows a chromatic cube as it can be used in some applicationsand in which the light-emitting surfaces can be formed with the versionsof μ-displays disclosed here;

FIGS. 34A and 34B show various embodiments of beam systems which can beplaced upstream, downstream or integrated into the imaging optics of thedevice of FIG. 29, 30 or 31;

FIG. 35 shows a schematic diagram for a first embodiment of a lightfield display according to some aspects of the proposed principle;

FIG. 36 illustrates the assembly of the first halftone image and thesecond halftone image to form a halftone image projected onto theretina;

FIG. 37 shows second pixel images with hexagonal outline;

FIGS. 38A to 38B show an adjustment optic with a switchable Bragggrating according to some aspects of the proposed concept;

FIG. 39 is a view of an adjustment optic with an Alvarez lensarrangement suitable for a light field display according to the proposedprinciple;

FIG. 40 shows an adjustment optic with a Moire lens arrangement suitablefor a light field display according to the proposed principle;

FIG. 41 shows an embodiment of a dynamic eye movement detection deviceand a control device for the adjustment optics of a light field displayaccording to the proposed concept;

FIG. 42 shows several examples of a one-dimensional pixel arrayaccording to some aspects of another concept;

FIG. 43 is an example to illustrate the rotation of the pixel rowaccording to some aspects of the proposed concept;

FIG. 44 shows another embodiment of a pixel array to illustrate a newlight generation and guidance concept;

FIG. 45 illustrates an embodiment of a pixel matrix with two pixelarrays according to the proposed principle;

FIG. 46 shows a third embodiment of a pixel array with several rows ofdifferent colors to illustrate a new light generation and guidanceconcept;

FIG. 47 shows another embodiment of a pixel array with rows for thedifferent colors according to the proposed principle;

FIGS. 48A and 48B show a cross-section of the pixel row of FIG. 47 witha photonic structure on a substrate and a top view of it;

FIGS. 48C and 48D show another embodiment of a pixel row, which isconfigured with redundant μ-LEDs;

FIGS. 49A and 49B show examples of embodiments of a pixel array withseveral subpixels of different size and frequency according to theproposed principle;

FIG. 50 shows another embodiment of a pixel matrix in which three rowsof pixels of different colors are offset from each other;

FIG. 51 is an embodiment of an optical system for generating an imageaccording to some aspects of the proposed concept of a one-dimensionalpixel array;

DETAILED DESCRIPTION

Augmented reality is usually generated by a dedicated display whoseimage is superimposed on reality. Such device can be positioned directlyin the user's line of sight, i.e. directly in front of it.Alternatively, optical beam guidance elements can be used to guide thelight from a display to the user's eye. In both cases, the display maybe implemented and be part of the glasses or other visually enhancingdevices worn by the user. Google'™ Glasses is an example of such avisually augmenting device that allows the user to overlay certaininformation about real world objects. For the Google™ glasses, theinformation was displayed on a small screen placed in front of one ofthe lenses. In this respect, the appearance of such an additional deviceis a key characteristic of eyeglasses, combining technical functionalitywith a design aspect when wearing glasses. In the meantime, usersrequire glasses without such bulky or easily damaged devices to provideadvanced reality functionality. One idea, therefore, is that the glassesthemselves become a display or at least a screen on or into which theinformation is projected.

In such cases, the field of vision for the user is limited to thedimension of the glasses. Accordingly, the area onto which extendedreality functionality can be projected is approximately the size of apair of spectacles. Here, the same, but also different information canbe projected on, into or onto the two lenses of a pair of spectacles.

In addition, the image that the user experiences when wearing glasseswith augmented reality functionality should have a resolution thatcreates a seamless impression to the user, so that the user does notperceive the augmented reality as a pixelated object or as alow-resolution element. Straight bevelled edges, arrows or similarelements show a staircase shape that is disturbing for the user at lowresolutions.

In order to achieve the desired impression, two display parameters areconsidered important, which have an influence on the visual impressionfor a given or known human sight. One is the pixel size itself, i.e. thegeometric shape and dimension of a single pixel or the area of 3subpixels representing the pixel.

The second parameter is the pixel pitch, i.e. the distance between twoadjacent pixels or, if necessary, subpixels. Sometimes the pixel pitchis also called pixel gap. A larger pixel pitch can be detected by a userand is perceived as a gap between the pixels and in some cases causesthe so-called fly screen effect. The gap should therefore not exceed acertain limit.

The maximum angular resolution of the human eye is typically between0.02 and 0.03 angular degrees, which roughly corresponds to 1.2 to 1.8arc minutes per line pair. This results in a pixel gap of 0.6-0.9 arcminutes. Some current mobile phone displays have about 400 pixels/inch,resulting in a viewing angle of approximately 2.9° at a distance of 25cm from a user's eye or approximately 70 pixels/° viewing angle and cm.The distance between two pixels in such displays is therefore in therange of the maximum angular resolution. Furthermore, the pixel sizeitself is about 56 μm.

FIG. 1A illustrates the pixel pitch, i.e. the distance between twoadjacent pixels as a function of the field of view in angular degrees.In this respect, the field of view is the extension of the observableworld seen at a given moment. This is because human vision is defined asthe number of degrees of the angle of view during stable fixation of theeye.

In particular, humans have a forward horizontal arc of their field ofvision for both eyes of slightly more than 210, while the vertical arcof their field of vision for humans is around 135°. However, the rangeof visual abilities is not uniform across the field of vision and canvary from person to person.

The binocular vision of humans covers approximately 114° horizontally(peripheral vision), and about 90° vertically. The remaining degrees onboth sides have no binocular area but can be considered part of thefield of vision.

Furthermore, color vision and the ability to perceive shapes andmovement can further limit the horizontal and vertical field of vision.The rods and cones responsible for color vision are not evenlydistributed.

This point of view is shown in more detail in FIGS. 1B to 1D. In thearea of central vision, i.e. directly in front of the eye, as requiredfor Augmented Reality applications and partly also in the automotivesector, the sensitivity of the eye is very high both in terms of spatialresolution and in terms of color perception.

FIG. 1B shows the spatial density of rods and cones per mm² as afunction of the fovea angle. FIG. 1C describes the color sensitivity ofcones and rods as a function of wavelength. In the central area of thefovea, the increased density of cones (L, S and M) means that bettercolor vision predominates. At a distance of about 25° around the fovea,the sensitivity begins to decrease and the density of the visual cellsdecreases. Towards the edge, the sensitivity of color vision decreases,but at the same time contrast vision by means of the rods remains over alarger angular range. Overall, the eye develops a radially symmetricalvisual pattern rather than a Cartesian visual pattern. A high resolutionfor all primary colors is therefore required, especially in the center.At the edge it may be sufficient to work with an emitter adapted to thespectral sensitivity of the rods (max. sensitivity at 498 run, see FIG.1D and the sensitivity of the eye).

FIG. 1C shows the different perceptual capacity of the human eye bymeans of a graph of the angular resolution A relative to the angulardeviation a from the optical axis of the eye. It can be seen that thehighest angular resolution A is in an interval of the angular deviationa of +/−2.5°, in which the fovea centralis 7 with a diameter of 1.5 mmis located on the retina 19. In addition, the position of the blind spot22 on the retina 19 is sketched, which is located in the area of theoptic nerve papilla 23, which has a position with an angular deviation aof about 15°.

The eye compensates this non-constant density and also the so-calledblind spot by small movements of the eye. Such changes in the directionof vision or focus can be counteracted by suitable optics and trackingof the eye.

Furthermore, even with glasses, the field of vision is furtherrestricted and, for example, can be approximately in the range of 80°for each lens.

The pixel pitch in FIG. 1A on the Y-axis is given in μm and defines thedistance between two adjacent pixels. The various curves C1 to C7 definethe diagonal dimension of a corresponding display from 5 mm toapproximately 35 mm. For example, curve C1 corresponds to a display withthe diagonal size of 5 mm, i.e. a side length of approximately 2.25 mm.For a field of view of approximately 80°, the pixel pitch of a displaywith a diagonal size of 5 mm is in the range of 1 μm. For largerdisplays like curve C7 and 35 mm diagonal size, the same field of viewcan be implemented with a pixel pitch of approximately 5 μm.

Nevertheless, the curves in FIG. 1A illustrate that for larger fields ofview, which are preferred for extended reality applications, very highpixel densities with small pixel pitch are required if the well-knownfly screen effect is to be avoided. One can now calculate the size ofthe pixel for a given number of pixels, a given field of view and agiven diagonal size of a μ-display.

Equation 1 shows the relationship between dimension D of a pixel, pixelpitch pp, number N of pixels and the edge length d of the display. Thedistance r between two adjacent pixels calculated from their respectivecenters is given by

r=d/2+pp+d/2.

D=d/N−pp

N=d/(D+pp)  (1)

Assuming that the display (e.g. glasses) is at a distance of 2.54 cm (1inch) from the eye, the distance r between two adjacent pixels for anangular resolution of 1 arcminute as roughly estimated above is given by

r=tan(1/60°)*30 mm

r=8.7 μm

The size of a pixel is therefore smaller than 10 μm, especially if somespace is required between two different pixels. With a distance, rbetween two pixels and a display with the size of 15 mm×10 mm, 1720×1150pixels can be arranged on the surface.

FIG. 2B shows an arrangement, which has a carrier 21 on which a largenumber of pixels, 20 and 20 a to 20 c are arranged. Pixels 20 arrangedside by side have the pixel pitch pp, while pixels 20 a to 20 c areplaced on carrier 21 with a larger pixel pitch pp. The distance betweentwo pixels is given by the sum of the pixel pitch and half the size foreach adjacent pixel. Each of the pixels 20 is configured so that itsillumination characteristic or its emission vector 22 is substantiallyperpendicular to the emission surface of the corresponding LED.

The angle between the perpendicular axes to the emission surface of theLED and the beam vector is defined as the collimation angle. In theexample of emission vector 22, the collimation angle of LEDs 20 isapproximately zero. LED 20 emits light that is collinear and does notwiden significantly.

In contrast, the collimation angle of the emission vector 23 of the LEDpixels 20 a to 20 c is quite large and in the range of approximately45°. As a result, part of the light emitted by LED 20 a overlaps withthe emission of an adjacent LED 20 b.

The emission of the LEDs 20 a to 20 c is partially overlapping, so thatits superposition of the corresponding light emission occurs. In casethe LEDs emit light of different colors, the result will be a colormixture or a combined color. A similar effect occurs between areas ofhigh contrast, i.e. when LED 20 a is dark while LED 20 b emits a certainlight. Because of the overlap, the contrast is reduced and informationabout each individual position corresponding to a pixel position isreduced.

In displays where the distance to the user's eye is only small, as inthe applications mentioned above, a larger collimation angle is ratherannoying due to the effects mentioned above and other disadvantages. Auser is able to see a wide collimation angle and may perceive displayedobjects in slightly different colors blurred or with reduced contrast.

FIG. 2A illustrates in this respect the requirement for the collimationangle in degrees against the field of view in degrees, independent ofspecific display sizes. For smaller display sizes such as the one incurve C1 (approx. 5 mm diagonal), the collimation angle increasessignificantly depending on the field of view.

As the size of the display increases, the collimation angle requirementschange drastically, so that even for large display geometries such asthose illustrated in curve C7, the collimation angle reaches about 10°for a field of view of 100°. In other words, the collimation anglerequirements for larger displays and larger fields of view areincreasing. In such displays, light emitted by a pixel must be highlycollimated to avoid or reduce the effects mentioned above. Consequently,strong collimation is required when displays with a large field of vieware to be made available to a user, even if the display geometry isrelatively large.

As a result of the above diagrams and equations, one can deduce that therequirements regarding pixel pitch and collimation angle becomeincreasingly challenging as the display geometry and field of view grow.As already indicated by equation 1, the dimension of the displayincreases strongly with a larger number of pixels. Conversely, a largenumber of pixels is required for large fields of view if sufficientresolution is to be achieved and fly screens or other disturbing effectsare to be avoided.

FIG. 3A shows a diagram of the number of pixels required to achieve anangular resolution of 1.3 arc minutes. For a field of view ofapproximately 80, the number of pixels exceeds 5 million. It is easy toestimate that the size of the pixels for a QHD resolution is well below10 μm, even if the display is 15 mm×10 mm. In summary, advanced realitydisplays with resolutions in the HD range, i.e. 1080p, require a totalof 2.0736 million pixels. This allows a field of view of approximately50° to be covered. Such a quantity of pixels arranged on a display sizeof 10×10 mm with a distance between the pixels of 1 μm results in apixel size of about 4 μm.

In contrast, the table in FIGS. 3B-1 and 3B-2 shows several applicationareas in which μ-LED arrays can be used. The table shows applications(use case) of μ-LED arrays in vehicles (Auto) or for multimedia (MM),such as automotive displays and exemplary values regarding the minimumand maximum display size (min. and max. size X Y [cm]), the pixeldensity (PPI) and the pixel pitch (PP [μm]) as well as the resolution(Res.-Type) and the distance of the viewer (Viewing Distance [cm]) tothe lighting device or display. In this context, the abbreviations “verylow res”, “low res”, “mid res” and “high res” have the followingmeaning:

very low res pixel pitch approx. 0.8-3 mmlow res Pixel pitch approx. 0.5-0.8 mmmid res Pixel pitch approx. 0.1-0.5 mmhigh res Pixel pitch less than 0.1 mm

The upper part of the table, entitled “Direct Emitter Displays”, showsinventive applications of μ-LED arrays in displays and lighting devicesin vehicles and for the multimedia sector. The lower part of the table,titled “Transparent Direct Emitter Displays”, names various applicationsof μ-LED arrays in transparent displays and transparent lightingdevices. Some of the applications of μ-displays listed in the table areexplained in more detail below in the form of embodiments.

The above considerations make it clear that challenges are considerablein terms of resolution, collimation and field of view suitable forextended reality applications. Accordingly, very high demands are placedon the technical implementation of such displays.

Conventional techniques are configured for the production of displaysthat have LEDs with edge lengths in the range of 100 μm or even more.However, they cannot be automatically scaled to the sizes of 70 μm andbelow required here. Pixel sizes of a few μm as well as distances of afew μm or even less come closer to the order of magnitude of thewavelength of the generated light and make novel technologies inprocessing necessary.

In addition, new challenges in light collimation and light direction areemerging. Optical lenses, for example, which can be easily structuredfor larger LEDs and can also be calculated using classical optics,cannot be reduced to such a small size without the Maxwell equations.Apart from this, the production of such small lenses is hardly possiblewithout large errors or deviations. In some variants, quantum effectscan influence the behaviour of pixels of the above-mentioned size andhave to be considered. Tolerances in manufacturing or transfertechniques from pixels to sub mounts or matrix structures are becomingincreasingly demanding. Likewise, the pixels must be contacted andindividually controllable. Conventional circuits have a spacerequirement, which in some cases exceeds the pixel area, resulting in anarrangement and space problem.

Accordingly, new concepts for the control and accessibility of pixels ofthis size can be quite different from conventional technologies.Finally, a focus is on the power consumption of such displays andcontrollers. Especially for mobile applications, a low power consumptionis desirable.

In summary, for many concepts that work for larger pixel sizes,extensive changes must be made before a reduction can be successful.While concepts that can be easily up scaled to LEDs at 2000 μm for theproduction of LEDs in the 200 μm range, downscaling to 20 μm is muchmore difficult. Many documents and literature that disclose suchconcepts have not taken into account the various effects and increaseddemands on the very small dimensions and are therefore not directlysuitable or limited to pixel sizes well above 70 μm.

In the following, various aspects of the structure and design of μ-LEDsemiconductors, aspects of processing, light extraction and lightguidance, display and control are presented. These are suitable anddesigned to realize displays with pixel sizes in the range of 70 μm andbelow. Some concepts are specifically designed for the production, lightextraction and control of μ-LEDs with an edge length of less than 20 μmand especially less than 10 μm. It goes without saying, and is evendesired, that the concepts presented here can and should be combinedwith each other for the different aspects. This concerns for example aconcept for the production of a μ-LED with a concept for lightextraction. In concrete terms, a μ-LED implemented by means of methodsto avoid defects at edges or methods for current conduction or currentconstriction can be provided with light extraction structures based onphotonic crystal structures. Likewise, a special drive can also berealized for displays whose pixel size is variable. Light guidance withpiezoelectric mirrors can be realized for μ-LEDs displays based on theslot antenna aspect or on conventional monolithic pixel matrices.

In some of the following embodiments and described aspects, additionalexamples of a combination of the different embodiments or individualaspects thereof are suggested. These are intended to illustrate that thevarious aspects, embodiments or parts thereof can be combined with eachother by the skilled person. Some applications require specially adaptedconcepts; in other applications, the requirements for the technology aresomewhat lower. Automotive applications and displays, for example, mayhave a longer pixel edge length due to the generally somewhat greaterdistance to a user. Especially there, besides applications of extendedreality, classical pixel applications or virtual reality applicationsexist. This is in the context of this disclosure for the realization ofμ-LED displays, whose pixel edge length is in the range of 70 μm andbelow, also explicitly desired.

A general illustration of the main components of a pixel in a μ-displayis shown schematically in FIG. 4A. It shows an element 60 as a lightgenerating and light emitting device. Various aspects of this aredescribed in more detail below in the section on light generation andprocessing. Element 60 also includes basic circuits, interconnects, andsuch to control the illumination, intensity, and, when applicable, colorof the pixel. Aspects of this are described in more detail in thesection on light control. Apart from light generation, the emitted lightmust be collimated. For this purpose, many pixels in microdisplays havesuch collimation functionality in element 60. The parallel light inelement 63 is then fed for light guidance into some optics 64, forfurther shaping and the like. Light collimation and optics suitable forimplementing pixels for microdisplays are described in the section onlight extraction and light guidance.

The pixel device of FIG. 4A illustrates the different components andaspects as separate elements. An expert will recognize that manycomponents can be integrated into a single device. In practice, theheight of a μ-display is also limited, resulting in a desired flatarrangement.

For light extraction and light guiding there are basically twopossibilities. In the first case, the eye of a user is directly in linewith the direction of radiation of a display. In such a case, the lightgenerated by the display can be radiated directly, collimated, enlargedor reduced. However, no more complex light guidance is necessary. Thistype of generation and guidance is often found in display applications,including the automotive sector. Also in applications to augmentedreality, using glasses can make use of this principle. The display isimplemented directly into the glasses and thus the glasses themselvesare used as a semi-transparent screen. Of course, this also requires theimplementation of control circuits and connection possibilities withtransparent material.

However, in some applications a light guide arrangement necessary forlight guidance, since the light-generating display is located outside auser's field of vision or at least not directly in front of it. Google'sGlass™ is an example of such an application.

FIG. 5 illustrates an example where the display is not within the lineof sight of the eye; that is, the light generated by the display must bedirected through the glasses to the eye. In FIG. 5, a μ-display 45,which has a light-generating element LED and an optical system 44 placedin front of the light path, is placed in a position outside the field ofvision of the eye. The light-generating element LED is one of thestructures presented above. It is substantially one or more smalldisplays with μ-LED pixels or subpixels thereof. A control is done bythe concepts also presented here. In case of a monolithic display, thecontrol can be implemented directly in the carrier. The μ-LED display isplaced on the carrier and electrically connected to it.

In the case of spectacles, the μ-display is located on the temples closeto the hinge. The μ-display in this example emits light of the primarycolors red, blue and green parallel to a feed element, which is built asa sandwich structure using elements 41, 43 g, 43 b, 42, 43 r and 43 b.The feed element has a first light guide 41 made of a transparentmaterial. A reflective input element 43 g is mounted on the sidewall ofthe light guide and opposite incident light to reflect the green portionof the light of the μ-display and guide it through the light guide 42.In some variants, the incident light has an angle of 0° to 45° withrespect to the surface of the corresponding light guide. In theillustrated example, the angle of light incidence is approximately 70°in relation to the surface of the light guide.

Another reflective coupler 43 b is either on or on element 43 g tocouple the blue component into the second light guide 42. Finally, thelast reflective element 43 r is positioned on the second light guide 42to reflect the red portion of the μ-display into the second light guide.To this extent, the reflective elements 43 are adapted to couple thecorresponding light portion into the light guides 41 and 42. Reflectivecoupling elements allow light to be coupled into light guides even ifincident light hits the light guide at a large angle, e.g. approximately70° to 90° as in FIG. 5. The first and second light guides are spacedapart using spacers 47 at both ends of the light guides.

The light guides 41 and 42 are both elongated and arranged parallel toeach other. They can be part of the glasses, for example. Totalreflection in both light guides prevents the light (the green part andthe red or blue part) from being coupled out of the light guide. Thelight is guided to an area in the light guide that is covered by thereflective out-coupling elements 46 r, 46 b and 46 g. All these areasare arranged on the same side as the areas of the correspondingreflective elements 43 g, 43 b and 43 r. Coupling element 46 r isarranged on the second light guide 42 and is configured to couple outthe red portion of the light from the second light guide and direct theportion to the eye. Elements 46 b and 46 g comprise the samefunctionality for the blue and green portions so that all three lightportions are substantially parallel and directed to the eye.

The couplers 43 are implemented using, for example, mirrors and thelike, which are reflective for a certain portion of the light butotherwise transparent. For the purpose of reflection, the couplers canchange the refractive index so that light is reflected. In a similarway, the change of refractive index between air and the light guideleads for example to the light inside the guide. The light is coupledout in a similar way. If the light of different colors is essentiallyparallel and overlapping, the corresponding coupling element(s) shouldbe stacked on top of each other. However, the stacking should occur insuch a way that the coupling element absorbs or reflects undesiredportions of the light. In some variants, MEMS mirrors can be used todirect the light coming from the display to the user's eye. In thisexample, the output coupler 46 is mounted directly on the light guide.

FIG. 6 shows an example of a light guide, in which a suitable beamguidance is achieved using a foveated display. FIG. 6 proposes anillumination arrangement of, for example, a μ-display, comprising alight-emitting optoelectronic element 1 and an optical device 6 for beamconversion or beam-shaping of the electromagnetic radiation generated bythe light-emitting optoelectronic element 1. In this context, alight-emitting optoelectronic element 1 comprises a plurality of μ-LEDs,which emit light of one color in operation. The light-emittingoptoelectronic element is designed so that the μ-LEDs emit differentcolors. As subpixels, three μ-LEDs form part of an entire pixel. Thelight-emitting optoelectronic element thus contains a large number ofsuch pixels.

The optical device 6 represents a system optic 19 in the form of animaging projection optic 20 and comprises in the beam path successivelya plane-parallel lens 21 and a first aspherical lens 22 and a secondaspherical lens 23, which realize an image of the light-emittingoptoelectronic element 1.

Furthermore, FIG. 6 shows that the light-emitting optoelectronic element1 comprises several emission regions 3.1, 3.2 arranged in matrix form.These each comprise one or more μ-LEDs (for different colors).Optionally, the μ-LEDs can already include primary optics 12. Theseprimary optics can contain converter elements, decoupling structures orphotonic crystals to achieve a certain beam-shaping already at lightemission. Each of the emission areas 3.1, 3.2 is assigned a main beamdirection 4.1 and 4.2. For at least partial compensation of the fieldcurvature arising in the optical device, the centers 7 of the emissionareas 3.1, 3.2 are arranged on a curved surface 5, which, for thepresent embodiment, forms a spherical segment 24 with an associatedspherical center 30 on the optical axis 10 of the optical device 6.

For a possible dimensioning, a radius R of 10 mm is selected for alight-emitting optoelectronic element 1 with a diameter D of 3.7 mm forthe curved surface 5 for the arrangement of the emission zones 3.1, 3.2and a material with a refractive index of at least 1.6 and a thicknessin the direction of the optical axis 10 of at least twice the diameter Dis required for the plane-parallel lens 21 of the optical device 1following in the beam path.

FIG. 7 shows an enlarged partial view of an example of an illuminationarrangement with a light-emitting optoelectronic element 1 comprisingseveral emission regions 3.1-3.5 formed by apertures of the primaryoptics of separate optochips 17.1 -17.5 in the form of μ-LEDs. Anarrangement of the separate optochips 17.1-17.5 on a non-planar ICsubstrate 16 is shown so that the centers 7 of the emission regions3.1-3.5 are located on a concave curved surface 5. Each of the emissionregions 3.1-3.5 forms a Lambert radiator 11 to which a main beamdirection 4.1-4.5 is assigned, whereby due to the nonplanar IC substratein the form of a spherical segment 24 facing the optical device 6, themain beam directions 4.1-4.5 comprise a common point of intersection onthe optical axis 10 of the optical device 6. By means of primary opticalelements 12 (cf. FIG. 6) the Lambertian emission of the emission regions3.1-3.5 can be transformed into a non-Lambertian emission, in particularinto an emission with a narrower aperture angle.

FIG. 8 shows an enlarged partial view of a design alternative with anoptical device 6, which is only shown in a sectional view, and a flat ICsubstrate 28 with a schematically simplified control device 25, whichtypically includes driver components and interface and memory elements.A monolithically pixelated optochip 14 is arranged on the flat ICsubstrate 28, which comprises a light-emitting optoelectronic element 1manufactured in a common process and having several emission regions3.1-3-5 lying on a concavely curved surface 5 of a region 15 of the chip14, which are each formed by a converter element 13. Corresponding tothe previous embodiment, the main radiation directions 4.1-4.5 of theemission regions 3.1-3.5 are at an angle to each other and intersect onthe optical axis 10 of the optical device 6.

FIG. 9 shows a fourth embodiment of an illumination device with alight-emitting optical element 1, comprising a stepped IC substrate 29,separate optochips 17.1-17 being mounted on concentrically arranged ringsurfaces 8.1, 8.2, 8.3 of the stepped IC substrate 29.5 formed by μ-LEDs11 are arranged in such a way that the centers 7 of the emission regions3.1-3.5 formed by primary optical elements 12 of the respective μ-LEDs11 lie on a concavely curved surface 5, while the main beam directions4.1-4.5 the emission regions 3.1-3.5 comprise a coincident orientation.Consequently, the distances of the separate optochips 17.1-17.5 to theplane-parallel lens 21 of the optical device 6 and thus the beamcross-section in the widening beam path in front of the optical device 6differ if they are arranged on different ring planes 8.1-8.3.

FIG. 10 shows a further development of the invention based on thevariant shown in FIG. 9, whereby a likewise concavely curved collimatingoptical element 18 is additionally arranged between the centers 7 of theemission zones 3.1-3.5 arranged on a concavely curved surface 5 and theplane-parallel lens 21 of the optical device 6. For the version shown,the collimating optical element 18 comprises a curved pinhole 26 and acurved microlens arrangement 27, which form a radiation angle filter.The functional components of the collimating optical element 18 can beassigned to one or more emission ranges 3.1-3.5. For a version not shownin detail, each functional component of the collimating optical element18 serves to pre-collimate several emission ranges 3.1-3.5 belonging toone pixel and radiating with different colors.

FIG. 11 shows an addition wherein the optochips 17.1 to 17.5 aredesigned as μ-LED arrays with an additional light-shaping structure onthe upper side of the emission surface. This improves light guidance andchanges the radiation characteristics of the individual optochips. Thelight-shaping structure, which is for example a photonic crystal in asemiconductor material of the optochip, results in a higherdirectionality of the emitted light. The light-forming structure can beformed in different ways.

FIG. 13 shows a further embodiment based on the example in FIG. 10, inwhich the light-forming structure 31 is arranged in the optical path ofthe optochips. It has several areas 30, 31 and 32 with a periodic changeof the refractive index. In particular, the regions are formed by holesin the material of structure 31, which produces the periodic variationof the refractive index. The holes for areas 30 and 32 are notperpendicular to the surface of the structure, but are etched at anangle to it. This etching thus causes a directional dependence of theholes and thus the variation of the refractive index. Correspondingly,such an arrangement produces a shaping of the light in the area shown inthe upper section of FIG. 13. Areas 30 and 32 are configured in such away that they collimate incident light and emit it again in a directedmanner at an angle defined by the direction of the holes. Only in area33 is light collimated. This special design of the photonic structureresults in an essentially parallel beam of light.

The embodiment of FIG. 12 is based on the example of FIG. 9, which alsoforms a light-shaping structure, but the width varies and follows theshape or surface of body 1.

FIGS. 14A and B show another design in cross-sectional view and topview. In this case, μ-LED modules 3 a, 3 b and 3 c are arranged asdescribed above on the concentrically arranged surfaces 8.1, 8.2 and 8.3of the stepped IC substrate, which are made up of several base modules.In a top view, this is shown in more detail by means of anotherembodiment, where the stepped substrate comprises rectangular steppedsurfaces. In the central i.e. “deepest” area 8.1 a μ-LED moduleconsisting of 4×5 base modules is arranged. In the next area 8.2 somemore μ-LED modules are shown. This can be a 2×8 module, but also have adifferent shape. Finally, the last section is partly already equippedwith a 1×13 module.

In addition to photonic structures, other light shaping measures canalso be provided directly on the substrate 29. FIG. 15 shows such anexample. In this case, a reflective structure 20 is arranged around eachemission range 3.1 to 3.5 or around each optochip 17.1 to 17.4. Thereflective structure 20 extends over the height of the emission surfaceso that light emitted at a flat angle is deflected laterally by thereflective structure. The reflective structure is formed with featuresfrom this application. For example, the optochips may be arranged incavities in each annular surface, the reflective structure 20 formingpart of the walls of the cavities.

FIG. 16 shows a combination of the embodiment based on the example inFIG. 8, with a large number of nanorods arranged on the surface, forexample those with a structure similar to the examples in FIGS. 26 to29. These are individually contacted and controlled by the controlcircuit 28.

A plurality of different projection units are known in the art, withwhich images can be displayed in specifically defined image planesaccording to requirements.

FIG. 17A shows a top view of a RGB emitter array with an optoelectroniclighting device 1 according to the state of the art, which is designedas a matrix with RGB pixels 40 emitting red, green or blue light. TheRGB-Pixel 40 are characterized by a high fill factor. This means that alarge part of the area 5 of the individual RGB pixel 40 is used aslight-emitting area.

FIG. 17B shows a schematic diagram of beam guidance in projection unitswith projection optics 7. Projection optics 7 comprises all 3 lensesshown in FIG. 17B, including the lens or plate 52. It can be seen thatthe radiation emitted by the individual RGB pixels 40 is not collimated.As shown in FIG. 17B, only the rays emitted by the RGB pixels 40 with anangle of radiation between +45° and −45° reach the elements ofprojection optics 7, which are arranged downstream of plate 52. Sincethe RGB pixels 40 emit light in accordance with Lambert's law ofradiation, without collimation of the radiation, therefore, part of theradiation emitted by the RGB pixels 40 cannot be used for imagegeneration, which ultimately means a loss of efficiency.

FIG. 18 shows a schematically simplified top view of an optoelectroniclighting device 1 with a proposed designed RGB emitter array accordingto some aspects disclosed here with six pixels, whereby the assignedpixel area 5 is shown for the exemplary pixel 2.1 provided withreference signs. Pixel 2.1 comprises separately applied μ-LEDs 3.1, 3.2,3.3 forming subpixels, which are adapted as μ-LEDs and which emit red,green and blue light for the embodiment shown. The individual pixels 2.1are characterized by a small fill factor so that only a comparativelysmall part of the pixel area 5 is occupied by the μ-LEDs 3.1, 3.2, 3.3.Otherwise, the μ-LEDs 3.1, 3.2, 3.3 are arranged in such a way that acomparatively large distance is formed between the individuallight-emitting areas of the subpixels. On the one hand, the μ-LEDs 3.1,3.2, 3.3 or the μ-LEDs are arranged at a distance from the edge of thepixels 2.1 so that optical and/or electrical crosstalk between adjacentpixels 2.1 does not occur. On the other hand, the μ-LEDs 3.1, 3.2, 3.3are also arranged within the individual pixels 2.1 in such a way thatoptical and electrical crosstalk between the individual semiconductorlighting devices 3.1, 3.2, 3.3 of a pixel 2.1 can be prevented or atleast minimized. The arrangement of the individual μ-LEDs 3.1, 3.2, 3.3takes into account the radiation characteristics and the light outputrequired to produce the desired images. In addition, a reflectiveelevation 2.4 can be designed, as shown here in the upper leftmostpixel. A transparent cover electrode can also be attached. Details ofthis are disclosed in this application.

FIG. 19A shows a complementary embodiment based on the example of FIG.18, where the pixels are arranged in rows and columns, each pixel havinga total of three sub-pixels formed by respective μ-LEDs 3.1, 3.2 and3.3. The individual μ-LEDs have different sizes depending on theiremitting color. μ-LED 3.2 for the green color has the largest area,since the human eye is particularly sensitive to the color green. Theμ-LED 3.1 for the red color and the μ-LED 3.3 for the blue color arearranged adjacent to the μ-LED 3.2 and have a significantly smaller sizein comparison. A reflective structure 2.1 is arranged around the μ-LEDs.This has a sloping side surface on which a reflective layer 21 isdeposited.

FIG. 19B shows the cross-sectional view along the XX-axis for a singlepixel. The individual μ-LEDs 3.1, 3.3.2 and 3.3 are designed as verticalLEDs and each have a contact surface on their underside. Each contactsurface is electrically connected to a contact area 3.11, 3.22 and 3.33in a planar substrate 3. A further contact on the light-emitting side ofeach μ-LED is connected to a conductive cover electrode. The coverelectrode is in turn connected to the conductive metallic and reflectivestructure 29 on all sides of the pixel. The reflective structurecompletely surrounds the μ-LEDs 3.1 to 3.3 and comprises a dielectricsupport 29 on the planar substrate 3, on which a reflective metal 21 isdeposited. This extends over the upper side of the structure 29 and isin electrical contact with the top electrode and along the sidewalls anda partial area of the backplane substrate 3. The metal 21 iselectrically insulated from the backplane substrate 3 by the electricalstructure 29. Due to the large reflection range through the reflectivelayer 21, light emerging from the side is reflected and radiatedupwards.

In the illustration shown in FIG. 19B the μ-LED 3.1 for the red light ispartly behind the μ-LED 3.3 for the blue light. The contact areas 3.11to 3.3 are designed accordingly, so that positioning the individualμ-LEDs on the surface of the backplane substrate 3 is simplified.

FIG. 20A shows a top view of another embodiment, in which a pixelelement with several subpixels is realized by horizontally arrangedμ-rods. The horizontally arranged rods correspond to the differentembodiments shown in this application. For each pixel, a common contactlevel 21 is provided on the backplane substrate, which on the one handcontacts the reflective metallic structure and on the other hand isconnected to a common terminal of each μ-LED 3.1-3.3. For individualcontrol of each μ-LED, the respective other contact area of this μ-LEDis coupled to a contact area on the surface of the backplane substrate.This contact area is designed larger than the diameter or width of therespective μ-LED, thus simplifying positioning. In the design of the toprow shown in FIG. 20A, two μ-LEDs 3.2 in the form of μ-rods are providedfor the color green. The μ-rods 3.1 are used to generate a red light,the μ-rods 3.3 to generate a blue light.

As already explained, the different widths of the μ-rods cause a coloremission during operation. Accordingly, the μ-rod 3.3 has the largestwidth for the blue color, the μ-rod 3.1 the smallest width. It isplanned to design the contact areas on the surface of the backplanesubstrate for individual control of the μ-rods with the same size ineach case. This provides additional flexibility in the assembly of theindividual pixels.

In the top row shown here, two rods are provided for the green color.Alternatively, however, the existing color space can be expanded, forexample by configuring the μ-rods differently for the green color. Suchan example is realized in the lower row in the left pixel with the twoRods 3.2 a and 3.2 b. Here the prod 3.2 b shows a slightly differentgreen color emission compared to the two Rods 3.2 a. Thus, the colorspace in the green area is extended. Another aspect is shown in thelower row, and concerns the different sensitivity of the human eye todifferent colors. In order to achieve an increased number of colorgradations or to prevent failure or defects, for example, an embodimentmay provide several μ-rods of one color in or for the pixel. In theright pixel of the lower line, this is represented by an additionalgreen μ-rod and an additional red μ-rod. These redundant μ-rods can beplaced on the pixel if necessary, i.e. if a defect is present. For thispurpose the contact areas, 3.11 and 3.22 are configured accordingly.

Another version shows the middle pixel of FIG. 20A. In this version, thecontact areas for the individual control of the rods are combined sothat all green and all red rods are controlled simultaneously. In thisrespect, a parallel connection of the three green and two red elementsshown here is achieved for both green and red μ-rods. The contact areason the surface of the backplane substrate 3 are larger, so that asimplified and more flexible positioning can be achieved.

In addition to the rods shown here, other embodiments of such a pixelwith different fill factors are also conceivable. FIG. 20B shows aversion with μ-LEDs 3.1 to 3.2 in the so-called bar shape presented inthis application. As already explained, a converter material 3.15 isarranged between two light-emitting bar-shaped elements 3.14 and thusforms a μ-LED. As shown, three μ-LEDs 3.2 for the green color arearranged in the top row of each pixel. Depending on the application, oneof these μ-LEDs can be designed as a redundant μ-LED to replace adefective μ-LED if necessary. Alternatively, it can be designed with adifferent green color to extend the color space. The bottom row ofpixels in FIG. 20B contains one μ-LED 3.3 for the blue color and twoμ-LEDs 3.2 for the red color.

FIG. 21 shows a top view of a matrix formed by RGB pixels, which formsan optoelectronic lighting device 1 of a proposed projection unit. As anexample, a pixel area 5 of pixel 2.2 is shown dashed. The pixel 2.2comprises three sub-pixel forming semiconductor lighting devices 3.1,3.2, 3.3, which emit red, green or blue light and which are arranged inthe form of a triangle on the surface 5 of the pixel 2.2. Thisembodiment may also be surrounded by a reflective layer. Another aspectat this point would be an embodiment as described above, in which thepixel emits light from the back, i.e. through the substrate, as shownschematically in FIG. 221.

Depending on the application, the matrix of pixels with μ-LEDs of asmall form factor presented here can be supplemented by a light-shapingor even light-converting structure. FIG. 22 shows a top view of such anembodiment. In this case, a light-shaping structure with areas 33 and 34is arranged on the matrix. The areas 34 are configured as pillars orcolumns or holes in the transparent layer 33 covering the matrix. Therefractive index of layer 33 is different from that of the columns 34 orholes 34. This results in a periodic variation of the refractive indexin the two spatial directions as shown in the top view. In this way, aphotonic structure or a two-dimensional photonic crystal is formed abovethe matrix of individual μ-LEDs and pixels. The light of at least onewavelength can thus be shaped appropriately by selecting the periodicityaccordingly. In addition, the columns or holes or even the μ-LEDsforming the subpixels can be arranged above one another. In this way,the holes or columns form a light guide, which can lead to animprovement of the radiation characteristic, an increased decouplingefficiency or an improved directionality.

Furthermore, FIG. 23 shows a schematic view of the different componentsof a proposed projection unit. Such a projection unit has anoptoelectronic lighting device 1, with matrix-forming pixels 2.1, 2.2,which have a low fill factor and each comprise μ-LEDs 3.1, 3.2, 3.3,which emit light of different colors, namely red, green and blue light.According to some suggested aspects, for each pixel 2.1, 2.2 acollimation optics 6.1, 6.2 is provided which collimates the lightemitted by the μ-LEDs 3.1, 3.2, 3.3 and images it into a preferablyvirtual intermediate image 8.1, 8.2. With the aid of a projectionoptical system 7, the intermediate image 8.1, 8.2 of the μ-LEDs 3.1,3.2, 3.3 is directed onto a display, screen or other display unit, whichmay also be the windscreen of a motor vehicle, which is not shownindividually, in order to produce an image which can be perceived by theobserver in the desired size, orientation and distance.

Furthermore, FIG. 24 shows the proposed location correction, which leadsto an overlay of the enlarged virtual intermediate images 8.1, 8.2 ofthe μ-LEDs 3.1, 3.2, 3.3. Consequently, the collimation optics 6.1, 6.2is designed in such a way that the size of the intermediate images 8.1,8.2 of the μ-LEDs 3.1, 3.2, 3.3 essentially corresponds to the size ofthe respective pixel 2.1, 2.2 and additionally the different positionsand sizes of the μ-LEDs 3.1, 3.2, 3.3 are largely compensated for thesuperimposition of the intermediate images 8.1, 8.2. Preferably theintermediate images 30.1, 30.2, 30.3 of the μ-LEDs 3.1, 3.2, 3.3 overlapover at least 85% and preferably over at least 95% of their intermediateimage area. The intermediate images 30.1, 30.2, 30.3 of the μ-LEDs 3.1,3.2, 3.3 may also overlap over at least 70%, 80% or 90% of theirintermediate image area.

It is also preferred that the total area of the overlapping intermediateimages 30.1, 30.2, 30.3 of the μ-LEDs 3.1, 3.2, 3.3 of the respectivepixel 2.1, 2.2 corresponds to at least 80% and preferably at least 90%of the pixel area 5. The total area of the overlapping intermediateimages 30.1, 30.2, 30.3 of the μ-LEDs 3.1, 3.2, 3.3 of the respectivepixel 2.1, 2.2 may correspond to at least 70%, 80% or 90% of the pixelarea 5.

The collimation optics 6.1, 6.2 assigned to each individual pixel 2.1,2.2 can be achieved by means of a holographic optical element (HOE), arefractive optical element (ROE) or a diffractive optical element (DOE).FIG. 25 shows the necessary chromatic phase function 12, 13, 14 of thecollimation optics 6.1, 6.2, 6.3 for the three different μ-LEDs 3.1,3.2, 3.3 of the respective pixel 2.1, 2.2. The upper graphic shows thechromatic phase function 12 for the μ-LED 3 emitting red light, themiddle graphic shows the phase function 13 of the collimation optics6.1, 6.2 for the green light emitting μ-LED 3.2 and the lower graphicshows the necessary chromatic phase function 14 of the collimationoptics 6.1, 6.2 for the blue light emitting μ-LED 3.3.

FIG. 26 shows an embodiment for which the collimation optics 6 isrealized with the help of a meta-lens 15. Such a meta-lens 15 can bedesigned to produce either a refractive optical element or a diffractiveoptical element. It is advantageous for such meta-lenses 15 to have atleast two spaced-apart regions, which have been structured in differentways. It is conceivable, for example, that in a first region of themeta-lenses a grid-like structure is provided, while the second regionof such a meta-lens 15 comprises a circular structure. It isadvantageous if the meta-lens 15 has a binary structure and/or is madeof a dielectric material at least in some areas. A further aspect onFIG. 296 results when taking into account that the column structure canbe arranged periodically or quasi-periodically. This results in an areawith a periodic variation of the refractive index.

FIG. 27 shows the side view of a monolithic optochip containing theoptoelectronic lighting device 1 for a projection display configured inaccordance with the invention. The optochip has a silicon substrate 9 onwhich the individual pixels 2 with the sub-pixels provided therein arelocated. In order to supply the optochip with the necessary electricalenergy, it has a power connection 11 and suitable conductor paths. Thepower supply and control of the individual light-emitting pixels 2 isprovided by a CMOS array 10. Light generation at the subpixels isrealized with LEDs, preferably μ-LEDs, which emit blue or ultravioletlight that is converted into light with the required color with the aidof suitable converter elements or suitable converter material.

On the surface of the optochip, there are pixels 2, in which subpixels50 are arranged, each emitting red, green and blue light. The individualsubpixels 50 each form a pixel 2 with a low fill factor, so that theindividual light-emitting areas within a pixel 2 only occupy a part ofthe area of pixel 2 in comparison to the areas that do not emit anylight, and are sufficiently spaced from one another in such a way thatoptical and electrical crosstalk between the individual subpixels 50 andbetween adjacent pixels 50 is reliably prevented or at leastconsiderably minimized.

The pixels 2, each formed by three subpixels 50, are each assigned acollimation optic, not shown in detail in FIG. 27, which causescollimation of the radiation emitted by the subpixels 3 and spatialcorrection. According to the invention, the collimation optics produce 6intermediate images of the subpixels 50 whose size corresponds to thesize of a pixel 2. In addition, the collimation optics must be designedin such a way that the different positions and sizes of the individualsub-pixels in the intermediate image are compensated. In addition to thedesign with a monolithic optochip shown in FIG. 27, it is alsoconceivable to arrange different chips, each having one or a pluralityof pixels or subpixels, on a common substrate and to contact themelectrically. Preferably, the subpixels 50 of pixel 2 are formed byLEDs, which emit light with the required color, especially red, green orblue light. In principle, it is conceivable here to use LEDs thatdirectly emit light with the desired color and/or convert the lightemitted by LEDs, especially blue light, into light with the requiredcolor with the aid of suitable converter elements and convertermaterials. It is also conceivable to design the subpixel 50 assuperluminescent diodes, VCSELs or edge-emitting lasers. It is alsoconceivable to implement the individual subpixel 50 s by means of fiberoptic cable end pieces that conduct light with the appropriate color.

In addition to the above version, the different resolution capabilitiesof the eye can also be taken into account by producing images ofdifferent resolution and directing them to the retina of a user.

As already mentioned, the central part of the fovea is dominated by thecones, whereas the rods are present over a larger angular range.Likewise, the increased cone density (L, S and M cones) means thatbetter color vision predominates, as the three different types of cones(L or also red, S or also green and M or also blue cones) registerdifferent color valences. Towards the edge, the sensitivity of colorvision is reduced in accordance with the lower cone density, but at thesame time contrast vision is maintained over a larger angular range bymeans of the rods, which are still active at low light intensity and aretherefore responsible for night vision. FIGS. 1B and 1D illustrate thisrelationship. Overall, a radially symmetrical visual pattern is thusformed for the eye. A high resolution of an image for all primary colorsis required, especially in the center. At the edge it may be sufficientto generate an image resolution adapted to the spectral sensitivity ofthe rods (max. sensitivity at 498 run, see FIG. 1B).

Small movements of the eye and a change in the direction of vision orfocus can be counteracted by suitable optics and tracking of the eye.

The optoelectronic device 1 of FIG. 28 comprises a μ-display or moregenerally an optoelectronic imager 2 for generating at least a first anda second image, and an imaging optic 3. The imaging optic 3 is adaptedto project a first image of the first image with a first resolution ontoa first region 4 of a retina 6 of the eye of a user and to project asecond image of the second image with a second resolution onto another,second region 5 of the retina 6, the first resolution being differentfrom the second resolution.

For this purpose, imaging optics 3 comprises a beam steering device 7,which comprises a movable mirror 7 a. The mirror 7 a, when appropriatelypositioned, directs light rays L4 a of the first image, for example tothe first region 4 a of the retina 6, to produce the first image and,after adjustment of its position, directs the light rays L5 a of thesecond image, for example to the second region 5 a of the retina, toproduce the second image. In the present case, the movable mirror 7 a istiltable about two axes, whereby the area illuminated on the retina canbe adjusted in both vertical and horizontal directions.

Furthermore, the imaging optics 3 comprises a beam-shaping device 8,which focuses the light rays of the first and second image on therespective area of the retina. The light rays L4 a of the first imageare focused more strongly than the light rays L5 a of the second image.

Since both the first and the second image are produced by only oneimaging device 2, and since this imaging device 2 has a certain totalnumber of pixels, the first and the different second resolution of thefirst and second image on the retina 6 is only produced by the differentfocusing of the light beams of the first image L4 a and the light beamsof the second image L5 a by the beam-shaping device 8. The resolution ofthe first and the second image results from the ratio of the pixelnumber of the imaging device 2 and the area of the respective image onthe first and second regions 4 a, 5 a of the retina 6, respectively.

Since a high resolution of a projected image on the retina is onlynecessary in the area of center 4, the first region 4 a with the firstand higher resolution is closer to the center of retina 6 than thesecond region 5 b with the second, lower resolution.

In the case of a retina 6 of an eye of a user of the optoelectronicdevice 1, which is to be assumed to be as round as possible, closer tothe center essentially means that the center of the first region 4 a,viewed in the radial direction, is closer to the center of the retina 6than the center of the second region 5 a. This means in particular thatthe resolution of the first and second images on the retina 6 is adaptedto the higher receptor density at the center of the retina 6.

Since the optoelectronic device 1 comprises only one image generator 2according to the embodiment of FIG. 28, the first image and second imageand further images are displayed on the image generator one after theother in time. As a result, an overall image composed of the at leastone first and one second image, i.e. a scene or a frame on the retina,is generated by a scanning process. The user only perceives the overallimage due to the rapid sequence of the individual images. Scanning inthis context means that the first and second image and possibly further,subsequent images are projected onto the areas of the retina one afterthe other, so that within a scene the entire surface of the retina isessentially completely illuminated by the images.

A marginal area 5 of the retina can be composed of several areas (e.g.area 5 a), which are illuminated with images of the same resolution.Similarly, a central area 4 can be composed of several areas (e.g. area4 a) that are illuminated by images with the same higher resolution.Between the edge region 5 and the central region 4 it is also possiblethat at least one intermediate region 10 is formed, which is composed ofseveral regions (e.g. 10 a) and is illuminated with images with the sameresolution. The edge region 5 and the at least one intermediate region10 each largely form a ring which is illuminated by several images. Thecentral area 4, on the other hand, largely forms a circle, which is alsoilluminated by several images. Illuminated areas of the retina mayoverlap. Preferably, however, the overlapping of areas is kept to aminimum. For example, less than 50% of the areas of the regions overlap,or less than 25% of the area of the regions, or less than 10% of thearea of the regions.

Since the individual images are projected onto the retina so quickly oneafter the other, the result is, as mentioned above, a “total image”composed of the individual images within a scene on the retina, which isperceived by the eye as one image. Typical image repetition frequenciesare 60 or 120 Hz and the display duration per frame is a fraction of aframe, whereby 2 to 100 partial images, preferably 5 to 50 partialimages, are displayed per frame.

Optionally, an additional lens 9 can be placed between the imager 2 andthe movable mirror 7 a in order to focus the light beams L emitted bythe imager and direct them to the movable mirror 7 a.

FIG. 29 shows two possible designs of the beam-shaping device 8, whichcan be either a classical lens with curved surfaces or a segmented lens.A different focusing of the first and second image with a classical lensis achieved in that a stronger focusing occurs under a light incidencewith a small angle to the optical axis than with beams with a largerangle to the optical axis.

The segmented lens, on the other hand, consists of several smallerlenses (mini-lens array) that focus to different degrees. Lenses 8 a areinstalled close to the optical axis of the system, which reduce theimage considerably, whereas lenses 8 b, 8 c project the image onto alarger area of the retina 6. As an alternative to a classical lens, thebeam-shaping device 8 can also be designed as a flat optical element,for example as a meta-lens. Especially in case of segmentation, thisoffers the advantage that individual areas can be structured directlyadjacent or smooth transitions between areas of different lensproperties are possible. For the overall system, the use of a flatoptical element for beam-shaping can enable a compact design.

The optoelectronic device 1 of FIG. 30 differs from the optoelectronicdevice 1 of FIG. 28 in particular in that the movable mirror 7 a isdesigned to tilt only about one axis. Furthermore, the beam-shapingdevice 8 can be formed from several optical elements, for example lenses8 a, 8 b with different imaging properties. By tilting the movablemirror 7 a, the at least one first and one second image generated by theimaging device 2 is sequentially projected onto the respective areas ofthe retina 6. The areas result as concentric circles that overlap intheir center. The following two options are possible for the imageformation of an “overall image”:

Each point on retina 6 is illuminated by only one projected image. Inother words, for N images, the imager produces N−1 times a ring-shapedimage with a dark central area, which is projected onto the retina 6.

Alternatively, at least one image generated by the imaging device canalso be projected onto the entire retina, whereby, viewed in the radialdirection, at least one second image in the center of the retina isprojected onto the central region of the retina 6 with a higher focusand thus higher resolution than the first image, and thus the cumulativestimulation of the at least two images corresponds to a desired targetvalue. In practice, this means that the basic stimulation that appliesto a larger area of the retina is produced at low magnification anddetails are produced at higher magnification settings by additionalstimulation. For this purpose, the image content is analysed by theelectronics of a system with regard to the spatial variation and brokendown into partial images corresponding to the different magnificationscales.

The optoelectronic device 1 of FIG. 31 differs from the optoelectronicdevice of FIG. 30 in that the beam steering device 7 has no movablemirrors but comprises at least two fixed beam steering elements 7 a/b.In addition, the optoelectronic device 1 comprises at least two imagegenerators 2 a, 2 b, which at least substantially simultaneouslygenerate a first and a second image. The first beam steering element 7 adirects the light rays L of the first image and the second beam steeringelement 7 b directs the light rays of the second image in the directionof the retina 6. By an appropriately selected design of the beamsteering elements 7 a/b, the images of the at least one first and onesecond image are focused in a different manner on the retina 6,resulting in a different resolution of the two areas. An additionalbeam-shaping device is not necessary for this embodiment.

The areas on the retina 6 result, as already for the design of theoptoelectronic device 1 of FIG. 30, as concentric circles overlapping intheir center. The following two options, among others, are possible forthe image formation of an “overall image”:

Each point on retina 6 is illuminated by only one projected image. WithN imaging devices and correspondingly with N simultaneously generatedimages, N−1 imaging devices generate a ring-shaped image with a darkcentral area, which is projected onto the retina 6.

Alternatively, the image generated by at least one imaging deviceilluminates the entire retina, whereby, viewed in the radial direction,at least one second image generated by a second imaging device isprojected in the center of the retina onto the central region of theretina 6 with a higher focus and thus higher resolution than the firstimage. The cumulative stimulation of the at least two images maycorrespond to a desired target value. In practice, this means that thebasic stimulation that applies to a larger area of the retina isproduced at low magnification and details are produced at highermagnification settings by additional stimulation. For this purpose, theimage content is analysed by the electronics of a system with regard tospatial variation and is broken down into partial images that correspondto the different magnification scales.

The at least two beam steering elements 7 a/b may, for example, beformed by fixed mirrors or have glass fibres.

With this embodiment, the imaging optics 3 can be made much simpler incomparison to the embodiments of FIGS. 28 and 30.

Nevertheless, by using several imaging devices, an adapted resolutioncan be achieved on each area of the retina.

The various configurations of a beamline as shown in FIGS. 28 to 31 canbe combined in any way, inter alia, with the various μ-displays anddisplay devices disclosed in this application.

FIGS. 32 to 33C show different configurations. In FIG. 32, light guidearrangement 3 is combined with a μ-display as shown in the configurationin FIG. 90. The μ-display 2 comprises a plurality of pixels arranged inrows and columns, each of which comprises a sub-pixel in the form of aμ-LED. The subpixels 3 a, 3 b and 3 c are designed to emit and guidelight of different colors. They are each surrounded by a reflectivestructure so that light emitted from the side is emitted upwards. Toimprove directionality, i.e. directional emission, a light-shapingstructure is applied to the μ-display and in particular above theindividual pixels. This comprises periodic areas with differentrefractive indices. For this purpose, a transparent material 33 isdeposited on the upper side of each pixel and each μ-LED and periodicholes 34 are formed in it. The resulting structure thus forms a2-dimensional photonic crystal, whereby the light emitted by the μ-LEDsis directed over the periodicity and radiated upwards in the form of acombined light beam L. Such collimation has the advantage that a moreprecise positioning on the retina of an observer is achieved by themirror 7 a and the lens system 8.

FIG. 33A shows a further embodiment in this respect. Instead of aμ-display with μ-LEDs with different color emission arranged on it,three different μ-displays are provided. Each individual μ-display P1,P2 or P3 comprises a large number of individual μ-LEDs arranged in rowsand columns, each of which can be individually controlled to emit aspecific color. The individual μ-displays P1, P2 and P3 thus generate acombined light beam, which falls on one of the mirrors 7 r, 7 g and 7 brespectively. The mirrors redirect the light beam and guide it via alens system Lr, Lg and Lb to the retina of an observer. In other words,the actual colored image is not already generated on the μ-display, butby the 3 different mirrors on the retina of the viewer. The individualcolor information is thus available separately for each pixel and isonly assembled on the retina of the observer. Compared to a μ-displaywith the subpixels of each color, this embodiment has the advantage thatthe size requirements of each μ-LED are slightly reduced. In contrast,there is of course a larger space requirement.

The individual μ-displays P1, P2 and P3 are realized in this embodimentby 3 different designs. It goes without saying, however, that only oneembodiment can be used for each individual μ-display. For example, theμ-display P1 for the red light comprises a plurality of horizontalμ-rods, which are contacted on the surface and can be individuallycontrolled. In this design, the μ-rods are each monochrome, i.e.designed to emit red light. Accordingly, the other μ-displays P2 and P3could also be equipped with such μ-rods to emit green and blue lightrespectively. Such a μ-display with horizontally aligned μ-rods ofdifferent colors is already shown in various other embodiments and canalso be realized here with the shown light guide arrangement.

Furthermore, in the representation of FIG. 33A, the μ-display P2 for thegreen light is implemented with an antenna slot structure according tothe proposed concept disclosed in this application. The antenna slotstructure comprises 2 antenna slots arranged in parallel for eachindividual green pixel. On the one hand, the parallel arrangement allowsa higher intensity and also allows compensating for possible defects bythe redundant arrangement of two antenna slots per pixel. In addition,as shown in this embodiment, the emitted green light is linearlypolarized due to the parallel arrangement of the antenna slots. In thisrespect, such an antenna slot structure as μ-display for each colorwould also be suitable for generating three-dimensional images on theretina of a user. In such a case, for example, the antenna slotstructure for the μ-displays of the other eye could be arranged 90°offset. The lens systems Lb, Lg and Lr could possibly have switchablepolarization filters.

A third version of a possible μ-display is realized by the μ-display P3.This comprises a plurality of monolithically integrated pixels of onecolor each, arranged in rows and columns. All μ-displays shown here canbe equipped with further measures for light coordination and lightshaping. For example, photonic structures of the surface or other lightforms of the elements such as microlenses are conceivable.

A further concept based on the embodiment of FIG. 32 and a μ-LEDarrangement according to FIG. 33A shows the embodiment of FIG. 33B. Theembodiment is adapted with 2 μ-displays 2 a and 2 b each, which containa large number of monolithically integrated μ-LEDs. Each subpixel can becontrolled individually. As explained in the embodiment for FIG. 32, thelight emitted by the μ-displays 2 a and 2 b is deflected by the twomirror systems 7 a and 7 b either to the central area of the eye of thefovea or to the more decentralized area 5. Accordingly, if theμ-displays 2 a and 2 b are configured in the same way, the resolution inthe fovea 4 area is higher than in the central area 5 due to theμ-display 2 b and the mirror system 7 b.

Finally, FIG. 33C shows a different embodiment in this respect with adichroic cube. The dichroic cube comprises 2 semi-reflecting surfacesperpendicular to each other. On three sides of the dichroic cube, thereis a μ-display of a plurality of μ-LEDs arranged in rows and columns.Each μ-display is designed to emit one color. In the example shown inFIG. 33C, the lower μ-display is used to emit a blue light, the rightμ-display to emit a green light beam and the left μ-display to emit redlight. The respective red and green light beams hit the surfaces of thedichroic cube in an angle and are deflected onto a lens system. Incontrast, the two surfaces of the dichroic cube are transparent to theblue light, so that it hits the lens system directly.

FIGS. 34A and 34B show two possible embodiments of beam systems 11,which can be arranged downstream of a respective imaging optics 3 of thedevice of FIG. 28, 30 or 31. The respective beam system 11 can thus bearranged between the imaging optics 3 and the eye.

The beam system 11 of FIG. 34A comprises an objective lens system 12 aand an eyepiece lens system 12 b, which are arranged successively in thebeam path between the imaging optics 3 and the retina 6 in order todirect the light rays L to the retina 6 following the imaging optics 3.Since the light path of the light rays L crosses in the beam system 11,the objective lens system 12 a produces an upside down and laterallyreversed real intermediate image 13 of the projected image. By means ofthe eyepiece lens system 12 b (principle of a magnifying glass), thisintermediate image 13 of the projected image is viewed magnified.

The beam system 11 of FIG. 34B, on the other hand, comprises only onelens system 12, which is arranged in the beam path between the imagingoptics 3 and the retina 6 in order to direct the light rays L to theretina 6 in the wake of the imaging optics 3. Correspondingly, no realintermediate image 13 of the projected image is produced in this lenssystem 11, but the projected image is merely viewed enlarged or reduced.

In a variant not shown, the respective beam system 11 could also bearranged between the imaging device 2, 2 a, 2 b and the imaging optics3.

It may be intended that the imaging optics 3 are integrated in the beamsystem 11. With reference to FIG. 34A, the imaging optics 3 could, forexample, be in the plane of the intermediate image 13. It may beprovided that a pair of lenses of lens system 12 b shown in FIG. 34A,which at least substantially defines the magnification, is spatiallysegmented (or at least one of the two lenses), and that the imagingoptics 3 lies between the spatially separated segments of a lens.Alternatively, the imaging optics 3 can also lie between the two lensesof the lens pair shown.

Also in the variant according to FIG. 34B, the shown lens pair of lenssystem 12 could include imaging optics 3, either as an additionalelement in between or as a modification of one or both lenses of thelens pair.

An alternative design to transfer images to or into the eye of a user isachieved by a Light field display which creates an image within the eyeby direct retinal projection. FIG. 35 shows a first version of a lightfield display 1 according to some of the principles presented here,which is explained below for the components assigned to a user eye.Binocular optics not shown in detail accordingly show a symmetricaldouble arrangement of the outlined components.

Shown in FIG. 35 is an optoelectronic device 2 and an optics module 4that create a retinal projection 5 of a raster image 3 in a user's eye6. The optoelectronic device 2 comprises a first imaging unit 10 with afirst μ-display 12 and a second imaging unit 11 with a second μ-display13. Both μ-displays are designed as μ-LED array with a plurality ofμ-LEDs in rows and columns. The μ-LEDs are organized as pixels, witheach pixel having three subpixels of different color. In other words,each μ-LED is designed to emit one color and is individually addressableand controllable.

For the embodiment shown, optics module 4 has a collimation optics 14and a projection optics 17 with a free-form lens 18, which produce afirst raster sub-image 8 of the first imaging unit 10 on the retina 19of the user's eye 6. The first raster sub-image 8 is created over alarge area.

For the imaging of the second imaging unit 11, an adjustment optic 15 isavailable in optics module 4, which is arranged within the collimationoptic 14 for the present embodiment. For other embodiments not shown indetail, the adjusting optics 15 can be located between the collimationoptics 14 and the projection optics 17 or at least partly in a waveguide16 of the projection optics 17.

The second raster sub-image 9 of the second imaging unit 11 is projectedonto a local area of the retina 19 with the fovea centralis 7, in whichthe most precise optical perception can be achieved due to the highsurface density of the visual cells, which are exclusively designed ascones for photo-optical vision. A higher resolution is selected for thesecond raster subimage 9 than for the first raster sub-image 8.

FIG. 1C shows the different perceptual capacity of the human eye bymeans of a graph of the angular resolution A relative to the angulardeviation a from the optical axis of the eye. The highest angularresolution A is in a region of the fovea centralis 7 with a diameter of1.5 mm on the retina 19, which covers an angle of about +/−2.5° aroundthe center (0°). In addition, there is a blind spot 22 on the retina 19at an angle of about −15°. FIG. 1C also illustrates the local limitationof the second projection area 21 of the light field display 1 for thehigh-resolution second raster sub-image 9 and the larger firstprojection area 20.1, 20.2 for the first raster sub-image 8 with a lowerresolution.

FIG. 36 illustrates the assembly of the first sub-image 8 and the secondsub-image 9 to form the halftone image 3 projected onto the retina 19.For the first raster sub-image 8, an activated first pixel image 24.1with a relatively low resolution is sketched with a solid line. Inaddition, two non-activated and dashed first pixel images 24.2, 24.3 ofthe first raster sub-image 8 are shown, whereby the representation inthese areas assigned to the fovea centralis 7 is replaced by anarrangement of second pixel images 25.1, 25.2, which are part of thehigher-resolution second raster sub-image 9. In order to keep an overlaparea of the two sub-images 8, 9 as small as possible, individual secondpixel images 25.3 can also be switched off for the advantageous designshown by an appropriate control of the second imaging unit 11.

FIG. 37 shows that the contours of the pixel images may differ from therectangular shape. Shown is a hexagonal version of the second pixelimages 25.4-25.10, which allows a high surface density. Techniques toproduce such μ-LEDs are disclosed in this application.

FIGS. 38A and 38B show a possible design of the adjustment optics 15.1,15.2 with the help of which the relative position of the retinalprojection 5 of the second halftone image 9 can be adjusted in relationto the retinal projection 5 of the first halftone image 8. Shown is aversion with a switchable Bragg grating 26, which has a holographicallyproduced pattern 27 with liquid crystal areas 28.1-28.n in a polymermatrix 29. FIG. 38A shows the state with an electric field oriented in afirst direction and an undeflected optical path 30.1 and FIG. 38B showsthe state with an electric field oriented in a second directionperpendicular to the first direction and a resulting deflected opticalpath 30.2.

An alternative embodiment of the adjustable optics 15.2 with anadjustable Alvarez lens assembly 31 is shown in FIG. 39. This comprisesa double arrangement with phase plates each having a surface relief,which can be moved relative to each other in the x and y direction forbeam adjustment. A special type of adjustable optics 15.3 with rotatingAlvarez lenses, called Moire lens array 32, is shown in FIG. 40.

FIG. 41 shows a further embodiment of the proposed light field display 1with a measuring device 34 to determine the position of the foveacentralis. For this purpose, a user eye 6 is illuminated by means of anIR illuminator 33 and an image of the retina 19 is taken. In the exampleshown, the second halftone image 9 (cf. FIG. 35) is dynamically adjustedso that the measuring device 34 is part of an eye movement detectiondevice 35 with which the direction of vision of the user can befollowed. By means of a control device 36 connected to the eye movementdetection device 35, the adjusting optic 15 is controlled in such a waythat the second halftone image 9 of the second imaging unit 10 is heldin the area of the fovea centralis, while the first halftone image 8 ofthe first imaging unit 11 remains stationary in relation to theoptoelectronic device 2. In addition, the control device 36 is connectedto a prediction device 37 in which a model of eye movement fed by thedisplayed image data D is calculated.

In addition to the concepts presented here for the production andstructuring of μ-LEDs and μ-Displays or modules, a special concept ofsuch a module is introduced in the form of a imaging element with avariable pixel density.

The inventors take advantage of the fact that the human eye does not seeequally well everywhere in its full range of vision, both in terms ofcolor perception and spatial resolution. Thus, an imaging element onlyneeds to have as good a resolution as is required for the respectiveareas in the eye.

FIG. 42 shows examples of a linear pixel array comprising a single rowof a plurality of μ-LEDs arranged side by side, or a monolithic LEDarray in which pixels in the μm range can be individually controlled.The row comprises a starting point A, to which the individual pixels Pof the row are connected along the axis X. These pixels areoptoelectronic components, which are set as μ-LEDs along the row or asmonolithic integrated components, possibly also in segments. Each pixelhas a fixed height h, but variable width l and comprises at least onelight-emitting element, for example a μ-LED. The pixels are arrangedcentrally around the axis X, and the pixels with the smallest width areclosest to the starting point A. In the embodiment shown, the pixelswiden with a fixed predetermined function, for example a linearfunction. The number of pixels in the row corresponds to the resolutionof the display to be shown. In other designs, the widening in width lcan follow the course of the sensitivity of the rods and cones of theeye. Thus, some adjacent pixels have the same width, others have adifferent width. Another possibility is a group widening, i.e. a numberof pixels along the axis comprise the same width or dimension, a secondgroup adjacent to it has a larger width. The latter way can beimplemented as a monolithic component in groups or segments.

In the second example, the pixels increase both in width l and height hwith increasing distance from the starting point. The change is chosenin such a way that a suitable rotation through an optical system resultsin a visual impression in which the pixels are each located on points ofcircles without any gaps between them. The number of pixels in the rowcan be in the range of several hundred pixels, but it can be less thanan HD resolution of 1980 pixel points per row.

In an example, about 150 pixels with the smallest width are arranged inone row from the starting point. The width can be 5 μm, for example.Then follows another group of 150 pixels with a pixel size of 10 μm. Twofurther groups with pixel sizes of 20 μm and 30 μm and a number of 100pixels or 50 pixels follow. This results in a total length of the row ofabout 5750 μm. However, with approximately the same effective visualresolution for the eye, the number of pixels is significantly reduced to500, which leads to a simpler and more cost-effective production.

In this context, it should be emphasized that the width between adjacentpixels is not always different, but can also be the same. In some cases,a pixel can also have a smaller dimension than an adjacent pixel closerto the starting point. However, the expression “width substantiallyincreasing from the starting point” means that the width of the pixelsincreases with distance over a larger number of pixels. The width, andpossibly also the height, therefore generally increases for pixels witha greater distance from the starting point, even though isolated pixelswith neighboring pixels may comprise the same dimension. Thus, theabove-mentioned execution of a segmental widening also falls under theabove-mentioned expression.

Using imaging optics, an image can now be generated by rotating thepixel array around the starting point. For this purpose, the pixel arrayitself is not rotated, but the light stripes generated by the pixelarray are shifted in fixed periods with an imaging optics, so that theimpression of a rotation around the starting point is created. If thisoffset occurs, fast enough, the inertia of the visual processing resultsin the impression of an image. The number of individual steps may or maynot depend on the height of the individual pixels. Depending on theimage, the period can also be selected in such a way that a certainoverlapping area results, especially in the high resolution area of theeye.

FIG. 43 shows a schematic representation of such a rotation. In contrastto the pixel row in FIG. 42, the height of each pixel is also variedhere and the height of the pixels increases with increasing distancefrom the starting point. This can be done in two ways. First, the heightof the pixels can actually be changed. Another way is to place anaperture above the pixel row so that the aperture widens. Thus, eachpixel resembles a trapezium rather than a square or rectangle. Thus,when the pixel row is rotated around the starting point, the step sizefor each pixel remains essentially constant and the “rotated” pixels lie“next to each other”. The height of a pixel can be approximatelydetermined by Hpixel >=2 d/nπ where d is the distance from the startingpoint to the pixel and n is the number of steps for a 360° rotation. Ifthe height of the pixels is selected to be larger, there will be anoverlap between pixels during the rotation.

FIG. 44 shows another embodiment in which the pixel array issymmetrically arranged along the X-axis around a center point thatrepresents the starting point A. The advantage of this arrangement isthat the imaging optics need only rotate the array by 180° to produce acomplete image.

FIG. 45 shows an embodiment of a pixel matrix with two pixel arraysarranged perpendicular to each other. The two pixel arrays have a commoncenter point around which the pixel density is greatest, i.e. the pixelshave the smallest size. During operation, the two pixel arrays generatea light cross along the axes X and X2, which can be rotated by adownstream optical system to generate a complete image. The arrangementwith two, or in alternative embodiments also several pixel arrays,allows a simpler design of the optics. In the example shown here, theoptics is configured to rotate the generated light cross by only 90, sothe pixel array is rotationally symmetrical by 90°.

FIG. 46 shows another aspect concerning the color perception of the eye.In the embodiment shown, several rows are arranged one above the otherwith subpixels of different colors. A column of subpixels of the colorsthus forms one pixel. The subpixels of each pixel of each row are, forexample, formed in the different basic colors R(Red), G(Green) andB(Blue). The rows of the different colors are arranged in a row “oneabove the other” along the axis. For example, the middle green row G islocated centrally on the X-axis of the row, a red row R and a blue row Bare adjacent to the first row with the green subpixels G on both sidesof the axis. In the example, the arrangement and especially the pixeldensity is the same for each row.

FIG. 47 shows an alternative embodiment in which pixels P and theirsubpixels of different colors are arranged in a single row. The pixelrow is arranged symmetrically around the starting point A. In theexample, the subpixels of each pixel P have different colors but thesame width. The width between the pixels increases continuously. Thepixels in the row that are further out, that is, those that are furtheraway from point A, also have a greater width. Alternatively, it can alsobe taken into account that the rods and cones in the eye also havedifferent relative color sensitivity at the same angle from the centerof vision. In order to compensate for this, the subpixels of differentcolors are also designed with different widths, i.e. with differentdimensions. If the current through the pixels remains constant, there isa different brightness of the color, so that the user has the impressionof equally bright colors at the respective location.

FIG. 48A shows a further embodiment in cross-sectional representation ofa pixel row according to the proposed principle. The mirror devicearranged above the pixel row can be rotated in 2 axes and can thusgenerate a circular image with different resolution for the user, asalready presented in this application. The pixel row itself is arrangedon a carrier substrate 20, which comprises different contact areas KBand K. In addition to the contact areas KB and K, the substrate 20 alsoincludes drive electronics, driver circuits, and power supply for theelectrical supply of the pixel array and the individual μ-LEDs. Thecontact areas KB are designed differently depending on the size of thepixel of the pixel row arranged above. This simplifies positioning andcontacting of the respective μ-LEDs of a pixel P of the pixel row. Inthis embodiment, a pixel P is made up of 3 subpixels R, G and B eachwith one μ-LED each. A central subpixel with one of the colors blue B isarranged rotationally symmetrically around the axis A. It has twice thesize of the adjacent green and red subpixels G and R.

As shown, the pixels P and the corresponding subpixels R, G and B andthe μ-LEDs show an increasing size with increasing distance from therotation axis A. For example, the μ-LEDs of the subpixels B, G2 and R ofthe outer pixels P are significantly larger than the μ-LEDs of thepixels adjacent around the central axis A. In addition, the μ-LEDs ofthe green subpixels G1 and G2 have larger dimensions compared to theother μ-LEDs of the same pixel as the distance from the rotation axis Aincreases. This is useful because the eye reacts more sensitively to thegreen color and thus the green color also dominates in peripheralvision.

The shown μ-LEDs are configured as vertical μ-LEDs. For this purpose,they have a common connection contact on the side facing away from thesubstrate 20, which is electrically connected to the contacts K on theoutside. A light-shaping structure in the form of a photonic crystalwith the areas 33 and 34 is applied to the upper side of thistransparent cover electrode. The areas 33 and 34 produce a variation ofthe refractive index and thus cause a collimation of the light emittedby the μ-LEDs.

The pixel row proposed according to this concept can be realized withμ-LEDs of different shapes and designs. FIG. 48B shows an embodiment inwhich the individual sub-pixels of each pixel are implemented in theform of so-called bars using μ-LEDs. A converter material is arrangedbetween a pair of μ-LEDs. At a greater distance from the centralsubpixel with the color blue B, the μ-LEDs emitting a green color aredesigned larger. This aspect considers the already mentioned increasedsensitivity of the human eye in the green range.

FIG. 48C shows a different embodiment. For each individual subpixel of acolor, a matrix of 2×2 μ-LEDs is provided, which are electricallyseparated from each other but optically connected. Thus, 2 essentialaspects can be realized. On the one hand, this design allows defectiveμ-LEDs to be sorted out and replaced by working μ-LEDs. This is shownfor example in the right area in the bottom row with a red subpixel,which is marked as defective as shown. The marked defective red μ-LED isreplaced by another μ-LED in the red subpixel. Additionally furtheroutside, a different intensity and radiation characteristic can beachieved by switching on additional μ-LEDs in the respective subpixel.This is indicated by the μ-LEDs of the green subpixel G1 and G2.

The structure shown in FIG. 48C comprises 4 μ-LEDs for each subpixel,some of which may be designed as redundant μ-LEDs. In a differentconfiguration, the matrix can also be a 2×1 matrix, with only a singlerow of 2 μ-LEDs per pixel. The decreasing resolution capabilities of theeye outside of an area of the fovea can be taken into account byenlarging the μ-LEDs. FIG. 48D shows the cross-sectional representationthrough the pixel structure of FIG. 48 shown in top view. Theembodiments of these μ-LEDs with optical and electrical separatingelements 16 as well as electrical separating elements 20 is alreadyexplained in this application in the embodiment of FIG. 133.

Finally, the two embodiments in FIGS. 49A and 49B take into account thatthe sensitivity of the eye to recognize colors also depends on the angleof vision and the distance to the center of the fovea, respectively. Thedependence of sensitivity is expressed by the fact that further outside,i.e. at a greater distance from the center, the eye no longer comprisesas many cones that react to the colors red and blue. Here the rods forthe color green predominate. Correspondingly, a variable, i.e. differentdensity is proposed for the respective pixels or subpixels of greencolor. While near the starting point A the subpixels of different colorare distributed essentially equally in the three rows, the row with thepixels for the color green predominates with increasing distance.

In FIG. 49A, the greater number of pixels of green is achieved byplacing the first row of green subpixels centrally along the X-axis,with essentially all pixel positions occupied. The other two rows R, Bwith the red and blue pixels are placed above and below the first row.Near the central starting point A, the pixel positions in all three rowsare occupied. With increasing distance, however, not all positions inthe second row R and the third row B are occupied, i.e. some positionsfor the red and blue pixels remain unoccupied. The occupancy density ofthe second and third rows decreases compared to the first row. Thisresult in a lower number of red and blue pixels compared to the greenpixels. In other words, the second and third rows are thus “shorter”than the first row.

In the alternative embodiment of FIG. 49B, the pixels of differentcolors are arranged along the X-axis similar to the embodiment of FIG.47. Close to the starting point, the pixels of rows R, G and B areequally distributed. As the distance increases, the density of pixels inrows R and B decreases, so that the pixels of the color greenpredominate in row G. At greater distances from the starting point A,the pixel row G with the green basic color then predominates.

It should be explicitly mentioned at this point that the differentaspects and examples can also be combined with each other to create adesired arrangement that makes sense for the respective application.This also, but not only, concerns the combination of rows and pixels inthe respective rows, i.e. combinations that relate to spatial resolutionand color sensitivity.

FIG. 50 shows another embodiment of a pixel matrix in which three rowsR, G, and B are offset from each other with pixels of different colors.The three rows have a common center A, and the angle between individualadjacent rows is 60°. Each row R, G, and B has pixels of the same color.In addition, the widths of the individual pixels of each row aredifferent (not shown here) to account for the different sensitivity. Thestaggered arrangement makes the realization easier, because the μ-LEDsof each row can be manufactured independently from the μ-LEDs of otherrows. By rotating the resulting image by means of an optical system by180, an approximately circular colored image is generated. In additionto this arrangement, the rows have different “lengths”. Furthermore, thepixel density of the individual rows of different color is alsodifferent. The row with the green color has the highest pixel density,because the eye reacts most sensitive to this. In the outer area, thepixel width of the rows R and B is increased, i.e. the spatialresolution is reduced there. In addition, rows R and B are somewhatshorter because the color sensitivity of the eye is reduced so much nearthe maximum distance that red and blue colors are no longer perceived.

FIG. 51 schematically shows an implementation of an imaging optic toconvert an imaging element with a variable pixel density into a virtualimage. The imaging element is a single pixel row with differentsubpixels that are designed to deliver a color. In addition to thispixel row, other imaging elements disclosed here can also be provided.The virtual image is created by a fast rotation of the light emitted bythe pixel array with several pixels in the user's eye. In particular,the pixel array generates a strip of light that corresponds to an imagerow in polar coordinates. The light is bundled by a first lens L1 anddirected to a first mirror S1. The first mirror S1 can be tilted aroundtwo axes that are perpendicular to each other, so it can deflect thelight strip around these two axes.

The light deflected by the first mirror is directed via another lens L2to a second mirror S2. This second mirror can also be tilted around twoaxes arranged perpendicular to each other. This functionality isexemplified in the figure by the two arrows. A third lens L3 focuses thegenerated light strip onto the user's eye. The light strip is nowrotated by a slight periodic tilting of the mirrors S1 and S2. Thetilting can be realized with MEMS or piezoelectric elements. With eachrotation, the image and color information desired at the new position isalso radiated from the PA pixel array. Due to the inertia of the eye, asufficiently fast rotation creates the impression of a circular image.The point of rotation in image Bi, for example, is placed in the focalpoint or direction of vision of the eye. A change in the direction ofview can be detected by eye-tracking measures. The mirrors S1 and S2 canthen follow the rotation point and deflect the image so that therotation point is again in the focus of the eye.

Each of the three lenses can be optional. Likewise, measures other thanlenses or mirrors, or other combinations of such optics, may be providedto produce the desired effect.

In the following, various devices and arrangements as well as methodsfor manufacturing, processing and operating as items are again listed asan example. The following items present different aspects andimplementations of the proposed principles and concepts, which can becombined in various ways. Such combinations are not limited to thoselisted below:

684. Optical fibre device, comprising:

-   -   a light-emitting device comprising at least two light-emitting        elements, in particular μ-LEDs, which emit light of two        different colors;    -   an elongated first light guide to guide light of a first color        and having an output part;    -   an elongated second light guide to guide light of a second color        and having an output portion;    -   a first coupling element disposed adjacent to the first light        guide and configured to reflect the light of the first color        into the elongated first light guide;    -   a second coupling element disposed adjacent to the second light        guide and configured to reflect the light of the second color        into the elongated second light guide.

685. Light guide device according to item 684, further comprising:

-   -   a third launching member mounted opposite the second launching        member and adjacent the elongated second light guide, the third        launching member being configured to reflect light of a third        color into the elongated second light guide.

686. Light guide device according to any of items 684 to 685, whereinthe first coupling element is transparent to light of a color differentfrom the first color.

687. Light guide device according to object 685, the second couplingelement being transparent to light of the third color.

688. Light guide device according to any of the preceding items, whereinthe light of different colors has an angle of incidence between 45° and90° with respect to the surface of the respective light guide

689. Light guide device according to any of the preceding items, wherelight of the third color has a wavelength greater than the light of thesecond color

690. Light guide device according to any of the preceding items, whereinat least one of the first and second coupling elements is arranged on asidewall of the respective elongated light guide.

691. Light guide device according to any of the preceding items, whereinthe first and second elongated light guides are substantially parallelto each other.

692. Light guide device according to any of the preceding items, furthercomprising spacer elements for spacing the first and second elongatedlight guides apart.

693. Light guide device according to any of the preceding items, furthercomprising

-   -   a first decoupling element arranged on the output part of the        elongated first light guide for decoupling light of the first        color;    -   a second out-coupling element arranged on the output part of the        elongated second light guide to couple out light of the second        color.

694. Light guide device according to item 693, further comprising:

-   -   a third out-coupling element arranged on the elongated second        light guide opposite the second out-coupling element to couple        out light of the third color.

695. Light guide device according to one of the objects 693 to 694,wherein the first decoupling element is transparent to light of thesecond and/or the third color.

696. Light guide device according to any of items 693 to 695, whereinthe second output coupler is transparent to light of the third color orthe third output coupler is transparent to light of the second color.

697. Lighting device comprising a light-emitting optoelectronic elementand an optical device for beam conversion of the electromagneticradiation generated by the light-emitting optoelectronic element

wherein said light-emitting optoelectronic element comprises a pluralityof emission regions arranged in a matrix form; and wherein each emissionregion is assigned a main beam direction; andat least part of the emission zones are arranged in such a way that thecenters of the emission regions lie on a curved surface.

698. Lighting arrangement according to item 697, characterized in thatthe curved surface has a concave curvature.

699. Lighting arrangement according to any of the preceding items,characterized in that the main directions of radiation of the emissionregions are at an angle to each other.

700. lighting arrangement according to any of the preceding items,characterized in that there are emission regions with a coinciding mainbeam direction, which are arranged on different planes at a differentdistance in the main beam direction from the optical device.

701. lighting arrangement according to any of the preceding items,characterized in that the curved surface forms a spherical segment, theassociated spherical center lying on the optical axis of the opticaldevice, or in that the curved surface has the shape of at least aportion of a rotated conical section, in particular an ellipsoid,paraboloid or hyperboloid.

702. Lighting arrangement according to any of the preceding items,characterized in that the emission regions whose centers are located onthe curved surface, each form Lambert radiators.

703. Lighting arrangement according to any of the preceding items,characterized in that at least one of the emission regions is theaperture of a primary optical element associated with a μ-LED or of aconverter element associated with a μ-LED.

704. Lighting arrangement according to any of the preceding items,characterized in that the emission regions whose centers lie on a curvedsurface are part of a monolithic pixelated optochip.

705. Lighting arrangement according to item 704, in which the monolithicpixelated optochip has a plurality of μ-LEDs arranged in rows andcolumns.

706. Lighting arrangement according to any of the preceding items, inwhich the emission regions constitute the surface of a coupling-outstructure, and which comprises a photonic crystal or photonic structurefor beam-shaping.

707. Lighting arrangement according to any of the preceding itemscharacterized in that the emission regions, whose centers lie on acurved surface, are assigned to separate μ-LEDs arranged on a non-planarIC substrate.

708. Lighting arrangement according to any of the preceding items,characterized in that the optical device comprises a system optic andbetween the system optic and the emission areas there is a curvedcollimating optical element or several non-planarly arranged collimatingoptical elements.

709. Lighting arrangement according to any of the preceding items,characterized in that the optical device comprises a system optic, whichforms an imaging projection optic.

710. Lighting arrangement according to any of the preceding items, inwhich the light-emitting optoelectronic element has a layer comprising aplurality of drive elements, in particular current sources forindividual drive of each of the emission areas.

711. Method of producing an illumination assembly comprising alight-emitting optoelectronic element and an optical device for beamconversion of the electromagnetic radiation generated by thelight-emitting optoelectronic element; wherein

the optoelectronic element comprises a plurality of emission regionsarranged in matrix form;characterised in thatat least part of the emission regions are arranged in such a way thatthe centers of the emission regions lie on a curved surface.

712. Method according to item 711, characterized in that separate μ-LEDsare arranged on a non-planar IC substrate to create the emissionregions.

713. Method according to any of the preceding items, characterized inthat at least one of the emission regions is formed by the aperture of aprimary optic associated with a μ-LED or a converter element associatedwith a μ-LED.

714. Light guide arrangement comprising a μ-display and a projectionoptics, wherein the μ-display comprises a matrix with pixels foremission of visible light and wherein each pixel comprises severalμ-LEDs with spectrally different light emission; and wherein each pixelis assigned a separate collimation optics preceding the projectionoptics, characterised in that

the collimation optics are configured in such a way that enlarged andoverlapping intermediate images of the μ-LEDs of the respective pixelare generated in the beam path in front of the projection optics.

715. Light guide arrangement according to item 714, characterized inthat the intermediate images of the μ-LEDs of the respective pixelgenerated by the collimation optics overlap each other over at least70%, 80% or 90% of their intermediate image area.

716. Light guide arrangement according to item 714 or 715, characterizedin that the intermediate images μ-LEDs are virtual intermediate images.

717. Light guide arrangement according to any of the preceding items,characterized in that the collimation optics is arranged between theμ-LEDs of a pixel and the projection optics.

718. Light guide arrangement according to any of the preceding items,characterized in that the μ-LEDs of a pixel occupy not more than 30%,particularly preferably not more than 15% and most particularlypreferably not more than 10% of the pixel area.

719. Light guide arrangement according to any of the preceding items,characterized in that the μ-LEDs are configured as color convertedμ-LEDs or as VCSELs or as edge-emitting laser diodes and optionally haveilluminated optical waveguide end pieces.

720. Light guide arrangement according to any of the preceding items,characterized in that the collimation optics are designed such that thetotal area of the overlapping intermediate images of the μ-LEDs of therespective pixel corresponds to at least 70%, 80% or 90% of the pixelarea.

721. Light guide arrangement according to any of the preceding items,characterized in that the collimation optics comprise a holographicoptical element (HOE) and/or refractive optical element (ROE) and/or adiffractive optical element (DOE).

722. Light guide arrangement according to any of the preceding items,characterised in that the radiation emitted by the projection optics isdirected directly or indirectly onto a display.

723. Light guide array according to any of the preceding items, in whicheach pixel comprises a μ-LED array according to any of the precedingitems.

724. Light guide arrangement according to any of the preceding items, inwhich each pixel comprises a μ-LED following one of the precedingobjects.

725. Light guide arrangement according to any of the preceding items, inwhich the μ-LEDs of a pixel are each formed by a horizontally arrangedmicrorod according to any of the preceding items.

726. Light guide arrangement according to any of the preceding items, inwhich the μ-LEDs of a pixel are each formed by at least one antenna slitstructure according to any of the preceding items.

727. Light guide arrangement according to any of the preceding items, inwhich the μ-LEDs of a pixel are each formed by a pair of emittingelements with a converter material arranged therebetween according toany of the preceding items.

728. Light guide arrangement according to any of the preceding items, inwhich the μ-LEDs of a pixel each comprise quantum well intermixing in anedge region of an active layer of the μ-LED.

729. Light guide arrangement according to any of the preceding items, inwhich the matrix comprises a light-shaping structure, in particular aphotonic crystal, which is in particular arranged at least partially ina semiconductor material of the μ-LEDs of the pixels.

730. Light guide arrangement according to any of the preceding items,further comprising a drive unit arranged in a substrate, in particularwith current drivers or current sources according to any of thefollowing items, wherein the μ-display is arranged on the substrate andthe pixels are electrically connected to the current drivers or currentsources.

731. Light guide arrangement according to any of the preceding items, inwhich a plurality of pixels of the matrix each have a microlens arrangedabove the μ-LEDs.

732. Light guide arrangement according to any of the preceding items, inwhich a plurality of pixels of the matrix has a reflection structurelimiting the pixels, in particular with features according to any of thepreceding items, which surrounds the μ-LED of the pixel.

733. Light guide arrangement according to any of the preceding items, inwhich at least some of the pixels of the matrix have a redundant μ-LED.

734. Light guide arrangement according to any of the preceding items, inwhich the matrix comprises a plurality of μ-LED base modules or aμ-display.

735. Light guide array according to any of the preceding items accordingto any of the preceding items, in which the pixels of the array comprisean optoelectronic device or a μ-LED array.

736. Use of a projection unit according to any of the preceding items toproduce an image in an augmented reality display unit, a virtual realitydisplay unit and/or on a head-up display.

737. Light guide arrangement comprising:

-   -   at least one optoelectronic imaging device, in particular a        μ-display for generating at least a first image and a second        image, and        at least one imaging optic adapted to project a first image of        the first image at a first resolution onto a first region of a        retina of a user and to project a second image of the second        image at a second resolution onto another, second region of the        retina, the first resolution being different from the second        resolution.

738. Light guide arrangement according to item 737, characterized inthat

the first region is closer to the center of the retina than the secondregion and thatthe first resolution is higher than the second resolution

739. Light guide arrangement according to any of the preceding items,characterized in that

the imaging optics comprises beam steering means which directs lightrays of the first image onto the first region and light rays of thesecond image onto the second region.

740. Light guide arrangement according to any of the preceding items,characterized in that

the imaging optics comprise at least one beam-shaping device whichfocuses the light beams of the first image more strongly than the lightbeams of the second image.

741. Light guide arrangement according to item 740, characterised inthat

the beam-shaping device comprises at least a first beam-shaping elementand a second beam-shaping element, the first beam-shaping elementfocusing the light beams of the first image and the second beam-shapingelement focusing the light beams of the second image.

742. Light guide arrangement according to any of the preceding items,characterized in that

the beam steering device for steering the beam has at least one movableand/or fixed mirror.

743. Light guide arrangement according to any of the preceding items,characterized in that

the beam steering device for steering the beam comprises at least oneand preferably at least two glass fibres.

744. Light guide arrangement according to any of the preceding items,characterized in that the first and the second image are temporarilydisplayed one after the other, especially on the same imager.

745. Light guide arrangement according to any of the preceding items,characterized in that

the first and second images are displayed at least substantiallysimultaneously, in particular on at least two different display devices.

746. Light guide arrangement according to any of the preceding items,characterized in that

said at least one optoelectronic imager is formed by a μ-display with aplurality of μ-LED arrays, in particular according to any of thepreceding items or a monolithic pixelated array.

747. Light guide arrangement according to any of the preceding items,characterized in that the second region concentrically encloses thefirst region.

748. Light guide arrangement according to any of the preceding items, inwhich the at least one optoelectronic imager comprises at least onematrix of pixels formed by a μ-LED arrangement according to any of thepreceding items.

749. Light guide device according to any of the preceding items, inwhich the at least one optoelectronic imager comprises a matrix ofpixels formed by one or more μ-LED according to any of the precedingitems.

750. Light guide arrangement according to any of the preceding items,wherein the μ-LEDs of a pixel are each formed by a horizontally arrangedmicrorod according to any of the preceding items, or wherein the μ-LEDsof a pixel are each formed by at least one antenna slot structureaccording to any of the preceding items.

751. Light guide arrangement according to any of the preceding items, inwhich the μ-LEDs of a pixel are each formed by a pair of emittingelements with a converter material arranged therebetween according toany of the preceding items.

752. Light guide arrangement according to any of the preceding items, inwhich the μ-LEDs of a pixel each have a quantum well intermixing in anedge region of an active layer of the μ-LED, in particular quantum wellintermixing.

753. Light guide arrangement according to any of the preceding items,further comprising a drive circuit according to any of the subsequentitems, which is implemented in a substrate from which the μ-display isarranged.

754. Light guide arrangement according to any of the preceding items, inwhich the μ-display of the at least one optical imager comprises amatrix with a light-shaping structure, in particular a photonic crystal.

755. Light guide arrangement according to item 754, in which thelight-shaping structure is at least partially arranged in asemiconductor material of the μ-LEDs of the pixels of the at least oneoptical imager.

756. Light guide arrangement according to any of the preceding items, inwhich the plurality of pixels of the at least one optical imager eachhave a microlens arranged above the μ-LEDs of each pixel.

757. Light guide arrangement according to any of the preceding items, inwhich the plurality of pixels of the at least one optical imager has areflection structure delimiting the pixels, in particular with featuresaccording to any of the preceding items, which surrounds the μ-LED ofeach pixel.

758. Light guide arrangement according to any of the preceding items, inwhich a first and a second optical imaging device, each comprising aμ-display, formed with μ-LED arrays, optoelectronic devices or μ-LEDsaccording to any of the preceding items.

759. Light guide arrangement according to any of the preceding items, inwhich at least some pixels of the matrix have a redundant μ-LED.

760. Light guide arrangement according to any of the preceding items,wherein the matrix comprises a plurality of μ-LED base modules or aμ-display.

761. Light guide arrangement according to any of the preceding items, inwhich the pixels of the array comprise an optoelectronic device or aμ-LED array.

762. Use of a light guide arrangement according to any of the precedingitems to produce an image in an augmented reality display unit, avirtual reality display unit and/or on a head-up display.

763. Light guide arrangement comprising:

-   -   at least three μ-displays, each comprising a matrix of pixels        arranged in rows and columns, each with at least one μ-LED,        configured to emit a light of a main wavelength    -   a projection unit, which is arranged in a beam path of each        μ-display and is designed to project images generated by the        μ-displays in overlapping manner onto an image plane, the image        plane being in particular a retina of an observer.

764. Light guide arrangement according to item 763, characterized inthat the projection unit comprises a lens or a mirror mounted in atleast one axis for each μ-display.

765. Light guide arrangement according to any of the preceding items, inwhich at least one glass fibre are used to direct the light of thedisplays onto the projection unit.

766. Light guide arrangement according to any of the preceding items,further comprising a collimation optics, which is configured to generateenlarged and overlapping intermediate images of the μ-LEDs of therespective pixel in the beam path in front of the projection optics.

767. Light guide arrangement according to any of the preceding items,wherein the matrix comprises a plurality of μ-LED base modules or aμ-display.

768. Light guide array according to any of the preceding items, in whichthe pixels of the array comprise an optoelectronic device or a μ-LEDarray.

769. Light guide arrangement according to any of the preceding items, inwhich the μ-LEDs of a pixel are each formed by a horizontally arrangedmicrorod or by at least one antenna slot structure or by a pair ofemitting elements with a converter material arranged therebetweenaccording to any of the preceding items.

770. Light guide arrangement according to any of the preceding items,further comprising a light-shaping structure on the pixels of eachμ-display, wherein the light-shaping structure is a microlens or aphotonic structure.

771. Light guide arrangement according to any of the preceding items, inwhich the μ-LEDs of a pixel comprise a reflective lateral surface.

772. Light guide arrangement according to any of the preceding items, inwhich a drive circuit is provided in a substrate, which comprises atleast one current driver circuit or a supply circuit, in particularaccording to any of the subsequent items for supplying at least onepixel, the μ-display being arranged on the substrate.

773. Light guide arrangement with

-   -   a dichroic cube;    -   three μ-displays with a matrix of pixels arranged in rows and        columns, one μ-display of which is arranged substantially        parallel to one side of the dichroic cube;    -   a light-emitting surface on the dichroic cube.

774. Light guide arrangement according to item 773, in which theμ-displays with the matrix of pixels arranged in rows and columnscomprise an optoelectronic device or a μ-LED arrangement.

775. Light guiding arrangement according to any of the preceding items,in which the pixels each comprise μ-LEDs formed by horizontally arrangedmicrorods or by at least one antenna slot structure or by a pair ofemitting elements with a converter material arranged therebetweenaccording to any of the preceding items.

776. Light guide arrangement according to any of the preceding itemsobjects, further comprising a light-shaping structure on the pixels ofeach μ-display, wherein the light-shaping structure is a microlens or aphotonic structure.

777. Light guide arrangement according to any of the preceding items, inwhich the μ-LEDs of a pixel comprise a reflective side surface.

778. Light guide arrangement according to any of the preceding items,further comprising collimation optics, which are designed to produceenlarged and superimposed intermediate images of the respectiveμ-display in the beam path according to the dichroic cube.

779. Light guide arrangement according to any of the preceding items, inwhich the light-shaping structure is at least partially arranged in asemiconductor material of the μ-LEDs of the pixels of the at least oneoptical imager.

780. Light guide arrangement according to any of the preceding items,further comprising a drive unit arranged in a substrate, in particularwith current drivers or current sources according to any of thesubsequent items, wherein the μ-display is arranged on the substrate andthe pixels are electrically connected to the current drivers or currentsources.

781. System, comprising:

a light guide arrangement according to any of the preceding items, anda control unit for controlling the image generator or the imaging opticsof the optoelectronic device, in particular in such a way that projectedimages of a frame of images, in particular comprising the first andsecond image, on the retina produce a coherent overall image.

782. System according to item 781, in which fuse elements areelectrically coupled to at least some of the μ-LEDs or pixels of theμ-displays, the at least some of the μ-LEDs or pixels forming redundantelements and the fuse elements activating the redundant elements ordeactivating them when not required.

783. System according to any of the preceding items, comprising supplydrivers, or control units having characteristics based on any of thesubsequent items.

784. System according to any of the preceding items, in which thecontrol unit is implemented in a substrate on which the μ-display isarranged and electrically connected to the control unit

785. Light field display comprising:

an optoelectronic device, in particular a μ-display for generating araster image;an optics module, for direct retinal projection of the raster image intoa user's eye;characterised in thatsaid optoelectronic device comprises a first imaging unit generating afirst raster sub-image and a second imaging unit generating a secondraster sub-image;wherein the raster image (or halftone image) comprises the first rastersub-image and the second raster sub-image; and the optics modulecomprises an adjustment optic for the retinal projection of the secondraster sub-image onto the fovea centralis in the viewer's eye; andwherein the retinal projection of the second raster sub-image has ahigher resolution than that of the first raster sub-image.

786. Light field display according to item 785, characterized in thatthe adjusting optics is configured in such a way that the relativeposition of the retinal projection of the second raster sub-image can beadjusted with respect to the retinal projection of the first rastersub-image.

787. Light field display according to any of the preceding items,characterized in that the retinal projection of the second rastersub-image in the user eye has a smaller spatial extension than theretinal projection of the first raster subimage.

788. Light field display according to any of the preceding items,characterized in that the adjusting optics comprises a switchable Bragggrating.

789. Light field display according to any of the preceding items,characterized in that the adjusting optics comprises an adjustableAlvarez lens arrangement.

790. Light field display according to item 789, characterized in thatthe adjusting optics comprises a Moire lens arrangement.

791. Light field display according to any of the preceding items,characterized in that a collimation optic is arranged in the beam pathof the first imaging unit and/or the second imaging unit.

792. Light field display according to item 791, characterised in thatthe adjusting optics is at least partially arranged in the collimatingoptics.

793. Light field display according to any of the preceding items,characterized in that the adjusting optics is arranged at leastpartially between the collimating optics and a waveguide.

794. Light field display according to any of the preceding items,characterized in that the adjusting optics are arranged at leastpartially in a waveguide.

795. Light field display according to any of the preceding items,characterized in that the first imaging unit and/or the second imagingunit comprises a μ-LED array having a plurality of μ-LEDs.

796. Light field display according to any of the preceding items,characterized in that the first imaging unit and/or the second imagingunit comprises a matrix of a plurality of μ-LED base modules or aμ-display.

797. Light field display according to any of the preceding items,characterized in that the first imaging unit and/or the second imagingunit comprise a matrix of optoelectronic device arranged in rows andcolumns or μ-LED arrangements.

798. Light field display according to any of the preceding items,characterized in that the first imaging unit and/or the second imagingunit comprises a matrix with a light-forming structure, wherein thelight-forming structure is a microlens or a photonic structure.

799. Light field display according to item 798, in which thelight-shaping structure is at least partially arranged in asemiconductor material of the μ-LEDs of the pixels of the at least oneoptical imager.

800. Light field display according to any of the preceding items,further comprising a drive circuit according to any of the followingitems, which is implemented in a substrate on which the μ-display isarranged.

801. Light field display according to any of the items 795 to 800,characterized in that the μ-LEDs comprise arrangements in which theμ-LEDs of a pixel comprise a reflective side surface.

802. Light field display according to any of the items 795 to 801,characterized in that at least some of the μ-LEDs form arrays or μ-LEDsform redundant elements which are separated from adjacent μ-LED arraysor μ-LEDs by electrically insulating but optically crosstalkingelements.

803. Light field display according to any of the items 795 to 802,characterized in that the μ-LED arrangements are configured to be ofdifferent sizes depending on the color, or that a total area of theμ-LED arrangements or μ-LEDs of a pixel is smaller than the area of thepixel, in particular only 50% to 70% of the area of the pixel.

804. Light field display according to any of the preceding items,characterized in that the light field display comprises a measuringdevice for determining the position of the fovea centralis.

805. Light field display according to any of the preceding items,characterized in that the light field display comprises an eye movementdetection device and a control device for dynamic tracking of theadjustment optics for the retinal projection of the second rastersub-image onto the fovea centralis.

806. Method of operating a light field display according to any of thepreceding items, characterized in that a first raster sub-image isimaged onto the retina of a user and a second raster sub-image, whichhas a higher resolution than that of the first raster sub-image, isimaged at least onto the fovea centralis in the user's eye.

807. Pixel array, in particular for a display in polar coordinates,comprising

-   -   a plurality of pixel elements arranged from a starting point on        an axis through the starting point in at least one row, wherein    -   the first plurality of pixel elements in planar view have a        length and a variable width such that the width of the pixel        elements substantially increases from the starting point.

808. Pixel array according to item 807, in which the starting pointforms a central point and the plurality of pixel elements are arrangedsymmetrically about the central point along the axis in a row.

809. Pixel array according to any of the preceding items, in which anytwo adjacent pixel elements of the plurality of pixel elements have atleast one of the following characteristics:

-   -   luminous areas of equal size, the distance between them        increasing with increasing distance from the starting point;    -   luminous areas, the corresponding increasing width of the pixels        becomes larger; or    -   a combination of these two possibilities.

810. Pixel array according to any of the preceding items, in which theplurality of pixel elements have a variable length such that the lengthof the pixel elements increases with increasing distance from thestarting point.

811. Pixel array according to any of the preceding items, where twoadjacent subpixels of the multiplicity of pixels have different colors.

812. Pixel array according to any of the preceding items, in which theplurality of pixel elements have at least three different colors, thenumber of pixels of each color being different.

813. Pixel array according to any of the preceding items, in which afirst number of said plurality of pixel elements are arranged in a firstrow and a second number of said plurality of pixel elements are arrangedin at least one second row, said first and second numbers of pixelelements having a different color in operation.

814. Pixel array according to item 813, in which pixels in each of atleast two rows have different colors in operation, the pixels beingarranged such that the n-th pixel of a first row has a different colorfrom an n-th pixel of the at least one second row.

815. Pixel array according to item 813, in which at least three rows ofpixel elements are arranged, the colors of which are different inoperation.

816. Pixel array according to any one of the items 813 to 815, in whichthe first row runs along a first axis and the at least one second rowruns along a second axis different from the first axis through a commoncenter point.

817. Pixel array according to any of the preceding items, in which thefirst number of the plurality of pixel elements in the first row isdifferent from the second number of the plurality of pixel elements inthe at least one second row.

818. Pixel array according to any of the preceding items, in which atleast some pixels of the first and at least one second row have the samewidth and from an n-th pixel of the first row onwards the width isdifferent from the width of the n-th pixel of the at least one secondrow.

819. Pixel array according to any of the preceding items, in which thefirst row and the at least one second row comprise pixels of differentcolors, and are arranged along the axis and starting from the startingpoint.

820. Pixel array according to any of the preceding items, where the rowwith the largest number of pixels preferably comprises pixel sin a greencolor.

821. Pixel array according to any of the preceding items, where from annth pixel of the first row onwards the width of adjacent pixels in thefirst row is smaller than that from the nth pixel onwards in the atleast one second row.

822. Pixel array according to any of the preceding items, where a numberof pixels of the color green is greater than a number of pixels of theother colors.

823. Pixel array according to any of the preceding items, in which theplurality of pixel elements in the at least one row are formed by amonolithically shaped pixelated array of μ-LEDs.

824. Pixel array according to any of the preceding items, in which atleast some of the plurality of pixel elements in the at least one roware formed by transferred μ-LEDs.

825. Pixel array according to any of the preceding items, in which theμ-LEDs each comprise a horizontally aligned microrod contacted on asubstrate.

826. Pixel array according to any of the preceding items, in which theμ-LEDs each comprise a pair of spaced light-emitting elements with aconverter material disposed therebetween.

827. pixel array according to any of the preceding items, in which theμ-LEDs have been manufactured by a process according to any of thepreceding items.

828. Pixel array according to any of the preceding items objects, inwhich at least some μ-LEDs are assigned redundant μ-LEDs of the samecolor, at least one of the μ-LEDs and the redundant μ-LEDs beingassigned a fuse element.

829. Pixel array according to any of the preceding items, in which theμ-LEDs are composed of μ-LED modules, each module comprising at leastone base module according to any of the preceding items, the number ofbase modules per μ-LED module increasing towards the outside.

830. Pixel array according to any of the preceding items, in which thepixel elements have a light-shaping structure, in particular areflective structure, a microlens or a photonic crystal.

831. Pixel array according to any of the preceding items, comprising asubstrate on which the pixel array is disposed, the substrate having asupply circuit or driver circuit following one of the following items.

832. Pixel matrix comprising at least two pixel arrays according to anyof the preceding items, in particular for a display in polarcoordinates, in which the at least two pixel arrays have a common centerpoint and enclose an angle substantially equal to 360° divided by twicethe number of the at least two pixel arrays.

833. Pixel matrix according to item 832, in which three pixel arrays areprovided, each of which has a different color.

834. Display arrangement in polar coordinates with an array or matrix ofpixels according to any of the preceding items, further comprising

-   -   an optical system comprising at least one mirror movable about        two axes, which is arranged in a main radiation direction of the        pixel array or pixel matrix and is adapted to rotate radiated        light from the pixels arranged in row about a point        corresponding to the starting point.

835. Method of operating a pixel array or a pixel matrix according toany of the preceding items, comprising the steps of;

-   -   creating a first light line with the multitude of pixel elements        arranged in a row;    -   guiding the first light line to a destination;    -   creating a second light line;    -   rotating the second light line by a certain angle and a rotation        point corresponding to the starting point of the pixel elements        arranged in line;    -   guiding the second light line to the destination.

The description with the help of the exemplary embodiments does notlimit the various embodiments shown in the examples to these. Rather,the disclosure depicts several aspects, which can be combined with eachother and also with each other. Aspects that relate to processes, forexample, can thus also be combined with aspects where light extractionis the main focus. This is also made clear by the various objects shownabove.

The invention thus comprises any features and also any combination offeatures, including in particular any combination of features in thesubject-matter and claims, even if that feature or combination is notexplicitly specified in the exemplary embodiments.

1. A lighting arrangement comprising: a light-emitting optoelectronic element; and an optical device for beam conversion of the electromagnetic radiation generated by the light-emitting optoelectronic element; wherein said light-emitting optoelectronic element comprises a plurality of emission regions arranged in a matrix; and wherein each emission region is assigned a main beam direction; at least part of the emission regions are arranged in such a way that the centers of the respective emission regions are located along a curved surface; and wherein at least one of the emission regions is the aperture of a primary optical element associated with a μ-LED or of a converter element associated with a μ-LED.
 2. The lighting arrangement according to claim 1, wherein the curved surface comprises a concave curvature.
 3. The lighting arrangement according to claim 1, wherein the main directions of radiation of the emission regions are arranged at an angle to each other.
 4. The lighting arrangement according to claim 1, wherein in emission regions having a coinciding main beam direction, which are arranged on different planes at a different distance in the main beam direction from the optical device.
 5. The lighting arrangement according to claim 1, wherein the curved surface forms a spherical segment, the associated spherical center lying on the optical axis of the optical device; or the curved surface comprises the shape of at least a portion of a rotated conical section, in particular an ellipsoid, paraboloid or hyperboloid.
 6. The lighting arrangement according to claim 1, wherein the emission regions whose centers are located on the curved surface, the centers forming Lambert radiators.
 7. The lighting arrangement according to claim 1, wherein the emission regions whose centers lie on a curved surface are part of a monolithic pixelated optochip.
 8. The lighting arrangement according to claim 7, in which the monolithic pixelated optochip comprises a plurality of μ-LEDs arranged in rows and columns.
 9. The lighting arrangement according to claim 1, in which the emission regions constitute the surface of a coupling-out structure, and which comprises a photonic crystal or photonic structure for beam-shaping.
 10. The lighting arrangement according to claim 1, wherein the emission regions, whose centers lie on a curved surface, are assigned to separate μ-LEDs arranged on a non-planar IC substrate.
 11. The lighting arrangement according to claim 1, wherein the optical device comprises a system optic and between the system optic and the emission areas there is a curved collimating optical element or several non-planarly arranged collimating optical elements.
 12. The lighting arrangement according to claim 1, wherein the optical device comprises a system optic, which forms an imaging projection optic.
 13. The lighting arrangement according to claim 1, in which the light-emitting optoelectronic element has a layer comprising a plurality of drive elements, in particular current sources for individual drive of each of the emission areas.
 14. A method of producing a lighting arrangement comprising a light-emitting optoelectronic element and an optical device for beam conversion of the electromagnetic radiation generated by the light-emitting optoelectronic element, wherein the optoelectronic element comprises a plurality of emission regions arranged in matrix form; and at least part of the emission regions are arranged in such a way that centers of the emission regions lie on a curved surface.
 15. The method according to claim 14, wherein separate μ-LEDs are arranged on a non-planar integrated circuit substrate to create the emission regions.
 16. The method according to claim 14, wherein at least one of the emission regions is formed by an aperture of a primary optic associated with a μ-LED or a converter element associated with the μ-LED.
 17. A light guide arrangement comprising: a pixel array, in particular for a display in polar coordinates, which: has a plurality of light emitting devices, μ-LEDs, μ-LED arrays or μ-LED modules which are arranged in at least one line starting from a starting point on an axis through the starting point, wherein the plurality of pixel elements have a height and a variable width such that the width of the pixel elements substantially increases from the starting point; or comprising a μ-display and a projection optics, wherein the μ-display comprises a matrix with pixels for emission of visible light and wherein each pixel comprises several μ-LEDs with spectrally different light emission; and wherein each pixel is assigned a separate collimation optics preceding the projection optics, wherein the collimation optics are configured in such a way that enlarged and overlapping intermediate images of the μ-LEDs of the respective pixel are generated in the beam path in front of the projection optics; or comprising: a light-emitting device comprising at least two light-emitting elements, including μ-LEDs, which emit light of two different colors; an elongated first light guide to guide light of a first color and having an output part; an elongated second light guide to guide light of a second color and having an output portion; a first coupling element disposed adjacent to the first light guide and configured to reflect the light of the first color into the elongated first light guide; and a second coupling element disposed adjacent to the second light guide and configured to reflect the light of the second color into the elongated second light guide. 